YouTube. Is YouTube a threat to the film industries or a democratic Essay

YouTube. Is YouTube a threat to the film industries or a democratic godsend to the masses - Essay Example Content available includes movie clips, video songs, TV shows and clips, video blogging, sports events, business management speech; user generated content and other types of video content (Miller, 2011). The company was acquired by Google in 2006 for 1.65 billion USD by Google. Only registered users are allowed to upload content and they can upload unlimited number of videos. Unregistered users can however view all types of barring movies flagged as premium. The viewership figures are very high. In 2010, more than 14 billion movies were viewed while 800 unique users visited the site every month. About 60 hours equivalent of new movies are uploaded to the site every minute (Anderson, et al, 2012). With such a large portfolio of movies and entertainment available, the statement that examined is ‘if YouTube is a threat to the film industries or a democratic godsend to people’. Thus, two issues will be examined and these are the threat to film industries and the advantages f or the masses. Various issues such as nature of content, partnerships formed with media houses, business model and other such issues are examined in detail. An analysis and discussion is then formed along with a conclusion. The position taken by the paper is that YouTube is not a competitor to media houses and the film industry but it acts as a channel partner and media outlet and that the masses use the services for learning new skills, entertainment, for advertisements and product demos. 1.1. Problems and issues faced by the film industry The film industry across the world is facing increasing competition, cannibalisation and parasitic behaviour by a number of entities. These include pirated and illegal CDs of movies that are sold for a few Pounds on the sidewalks and which are also available as illegal downloads. Then there are the satellite channels such as HBO, Star Movies and others that broadcast reruns of old movies by paying some amount to the movie production house. Then t here are websites such as NetFlix that offer legal movies on rent but the revenue earned by the film producer is less. The film industry makes profits mainly when patrons visit movie theatres (Jenkins, 2009). People tend to stay away from theatres since they can view movies through other legal and illegal channels. People will of course flock to the movie theatres to see hit films such as Avatar and the Harry Potter series but older movies see near empty houses. In such a case, a movie-sharing website such as YouTube that offers movies free viewing would be highly unwelcome since the website will further reduce the revenue (Lievrouw and Livingstone, 2012). The point is that the film industry would stand to suffer monetary loss and not loss of any reputation or identity theft since YouTube would not claim that a particular movie was filmed in-house. However, media houses are willing to consider services and offers that help them to obtain additional revenue. This issue is examined in the next section. 2. Analysis of YouTube Some important topics are first analysed with reference to the business model and content related topics. Observations from these discussions will be used in arguing for the statement. 2.1. Business Model Used The business model used by YouTube is advertisement revenue obtained from click through rates by users when they visit pages that host the movies. Advertisers pay a certain amount to the website to carry the Ads. It differs from the retail model of Netflix and Spotify in that it does not directly charge rentals for movies that are hosted. It is somewhat similar to Napster and Limewire but YouTube does not encourage illegal hosting of movies and it is not possible to download movies easily unless some special

Course Syllabi- History of Graphic Design Essay Example for Free

Course Syllabi- History of Graphic Design Essay Course Description History of Graphic Design is a critical contextual research and survey study of the intents, influences, practices, and artifacts of graphic design. The course will be structured on readings, research, and visual presentations on subjects of designer activities throughout history with an emphasis on the broader historical context of the planning, production, form, distribution, reception and cultural integration of graphic design Student Handbook The Student Handbook is now available digitally rather than in hard copy. It can be found on the PNCA website (under Student Life) and on Homeroom (Home page, under PNCA Essentials). Disability Support PNCA is in compliance with federal law requiring colleges to provide reasonable accommodations for students with documented physical and/or learning disabilities. If you have a disability that might affect your performance in this class, please make it known to the instructor. Learning Outcomes At the conclusion of this course, the student should be able to : - ­Ã¢â‚¬  Demonstrate and articulate in discussions, writings, and visual presentations an understanding of the historical context of the creation of a work of graphic design (i.e. time, place, culture, intents) - ­Ã¢â‚¬  Synthesize readings and lectures and be able to formulate and post discussion points and prepare visual examples for peer review and feedback (as comments) using online tools - ­Ã¢â‚¬  Utilize, and bibliographically document, a range of resources used for the study of the history of graphic design (books, journals, periodicals, online, interviews) - ­Ã¢â‚¬  Creative Practice Identify the roles, activities, and trades of communication design professionals throughout history and distinguish specific fields related to and integrated with the profession of graphic design - ­Ã¢â‚¬  Learning Outcomes are linked to PNCA’s Core Values which are: Identify and articulate the influence of fine art (theories, trends, aesthetics, visual styles) on the work of graphic designers Integrated Knowledge, Critical Thinking, Cultural Inquiry Social and Ethical Responsibility Course Content initiate, and participate in, discussion on the planning, process, production and distribution of works of graphic design - ­Ã¢â‚¬  Effective Communication - ­Ã¢â‚¬  formulate a connection of the cultural influences on design from history with practices of contemporary graphic designers through examples, writings, and discussions Assignments for this Class: - ­Ã¢â‚¬  - ­Ã¢â‚¬  - ­Ã¢â‚¬  - ­Ã¢â‚¬  Required Readings and discussion with evidence of comprehension Weekly Subject Research and On-line Posting to Homeroom Weekly In-Class presentations Final Research Paper Topics for weekly research will include: Design during Cultural Upheavals / World Conflicts Design for Social Causes / Design for Social Good Design for Commerce, Consumption, Commercialism Information Design / Dissemination and Distribution of Information Technological Changes and its Influence on Graphic Design Design as Author, Designer as Artist, Whole Designer The Concept of Brand and the Development of Brand Identity Low Design / Bad Design Major Benchmarks in Typography Reactionary Design / Culture Jamming Expectations/Policies for this course: Students are required to read and to be ready to articulate a response to all readings assigned in class. Each week there will be an assigned subject research topic that will require independent sourcing, image documentation, writing, and on-line posting on the ‘Homeroom’ site established for the course. Each student will make a 5-10 minute presentation of each assignment postings during classtime with an expectation of the use of prepared supported notes for verbal elaboration on the material presented. In-class and on-line participation in the form of response and discussion and will be expected and recorded. A final research project on the relatedness of the topics of historical practice presented to the practices of a contemporary designer or design firm/group will be in the form of a research paper. (8-10 pages minimum) Attendance You will be allowed two absences without additional penalty although you are responsible for any work that is missed. The third absence will result in the lowering of an entire letter grade from the computed final grade. A fourth absence will result in a final failing grade of F. Missing 30 minutes of a class period (during any part of the scheduled classtime) counts as an absence. Frequent tardiness (less than 15 minutes) will accumulate to absences (3 tardies =1 absence) Number of hours students are expected to work outside of class: This class meets for three hours per week, and six hours of work outside of class are expected. (3 credits) Grading Criteria †¢ Weekly Research Assignments timely completion / in-class presentation preparedness and comprehensiveness †¢ In-Class participation/contributions †¢ On-Line participation/contributions †¢ Final Research Paper Materials / Supplies Required: †¢ Access to, or ownership of, equipment to scan/photograph (digitize), upload and review visual and text information on a regular daily basis. (Computer and Camera/Scanner) †¢ Money for photocopying (approx. $20 projected) †¢ Flash Drive (2-4gb) Recommended: History of Graphic Design text purchases (Personal library) Bibliography The books listed here are predominantly larger volumes dedicated to a broad overview and history of graphic design. (More may be added during the semester) Many less comprehensive but key texts are available in the library as well as journals and periodicals that are specific to designers, styles, and various other edited groupings – these should be sought out and reviewed andutilized especially for more indepth study on a research subject. Major Texts of the History of Graphic Design Those mark with asterisk* are on reserve shelf at front desk of PNCA library and are available on 3 hr. check out (note: many of these text have duplicates or earlier editions and are available for longer check out periods if needed) Title: Meggs, History of Graphic Design, 4th Edition* Author(s): Philip Meggs, Alston Purvis Publisher: Wiley ISBN: 978047169902 Library Call#: Z 246 .M43 1983 Title: Graphic Design, a Concise History* Author: Richard Hollis Publisher: Thames Hudson world of art ISBN 0500203474 Library Call#: NC 998 .H65 1994 Title: Graphic Design: a New History* (1st and 2nd Editions) Author: Stephen Eskilson Publisher: Yale University Press ISBN: 0300120117 Library Call#: NC 998 .E85 2007 (1st Edition in Library*) Students are invited to contribute to the additions to this bibliography through their weekly research and presentation. All sources should be cited using MLA citation methods. Title: Graphic Design History, A Critical Guide* Author(s): Johanna Drucker, Emily McVarish Publisher: Pearson/Prentice Hall ISBN: 0132410753 Library Call#: NC 998 .D78 2009 Title: Graphic Design in America* Author(s): Mildred Friedman, Joseph Giovannini, Steven Heller Publisher: Walker Art Center ISBN: 0810910365 Library Call#: NC 998.5 .A1 G65 Title: Design, Writing, Research* Author(s): Ellen Lupton, Abbot Miller Publisher: Kiosk ISBN: 1568980477 Library Call#: Z 246 .L86 1996 Title: Communication Design, Principles, Methods, and Practice Author: Jorge Frascara Publisher: Allworth Press ISBN: 1581153651 Title: A Century of Graphic Design Author: Jeremy Aynsley Publisher: Barron’s Educational Series ISBN: 0764153242 Library Call#: NC 998.4 .A96 2001 Other Readings: Journal: Visible Language 28.3, New Perspectives, Critical Histories of Graphic Design, Pt. 1 Critiques Editor and Publisher: Sharon Poggenpohl Digital reference (Links) sites should be added to online postings On-Line History of Graphic Design Reference www.designhistory.org Weekly Course Schedule Week 1 6 Sept Week 2 13 Sept Friday, 13 September is the last day to add or drop a class. All information (dates, times and assignments) in this schedule is subject to change at any point during the semester. Updates will be announced and posted. Welcome / Introductions Class Expectations / Syllabus Overview / Course Structure / Assignments Using Homeroom / Communication Expectations Course Resources Reading Assigned (Posted on Homeroom) Critical Histories of Graphic Design Discussion of Readings on the approaches to History of Graphic Design development Lecture: Brief History of Graphic Design, Pt.1 Read on Homeroom these posted excerpts for this class: Graphic Design History, a critical guide, by Drucker and McVarish, Communication Design, Principles, Methods, and Practice, by Frascara, Graphic Design, a Concise History, by Hollis, Megg’s History of Graphic Design, by Meggs and Purvis, Visible Language 28.3 New Perspectives: Critical Histories of Graphic Design, article by Blauvelt Also read (for this classes visual lecture): â€Å"Prehistoric Prelude to Graphic Design† from Graphic Design History, a Critical Guide, by Drucker and McVarish Week 3 20 Sept Lecture: Brief History of Graphic Design, Pt.2 Read on Homeroom these posted excerpts for this class: â€Å"Early Writing: Mark Making, Notations Systems, and Scripts† from Graphic Design History, a Critical Guide, by Drucker and McVarish Lecture: Conventions and Norms Overview of Weekly Research Project Topics, Objectives, Goals, Expectations, Methods Introduction of Topic 1: Design during Cultural Upheavals / World Conflict Week 4 27 Sept Student Research Presentations of Topic 1: Design during Cultural Upheavals / World Conflict Questions and Discussion Introduction of Topic 2: Design for Social Causes / Design for Social Good Week 5 4 Oct Student Research Presentations of Topic 2: Design for Social Causes / Design for Social Good Questions and Discussion Introduction of Topic 3: Design for Commerce, Consumption, Commercialism Week 6 11 Oct Student Presentations of Topic 3: Design for Commerce, Consumption, Commercialism Questions and Discussion Introduction of Topic 4: Information Design / Dissemination and Distribution of Information Week 7 18 Oct Student Presentations of Topic 4: Information Design / Dissemination and Distribution of Information Questions and Discussion Introduction of Topic 5: Technological Changes and its Influence on Graphic Design Week 8 25 Oct Student Presentations of Topic 5: Technological Changes and its Influence on Graphic Design Questions and Discussion Introduction of Topic 6: Design as Author, Designer as Artist, Whole Designer Friday, 25 October is the last day to withdraw from a class. Week 9 1 Nov Student Presentations of Topic 6: Design as Author, Designer as Artist, Whole Designer Questions and Discussion Introduction of Topic 7: The Concept of Brand and the Development of Brand Identity Week 10 8 Nov Student Presentations of Topic 7: The Concept of Brand and the Development of Brand Identity Questions and Discussion Introduction of Topic 8: Low Design / Bad Design Week 11 15 Nov Student Presentations of Topic 8: Low Design / Bad Design Questions and Discussion Introduction of Topic 9: Major Benchmarks in Typography Week 12 22 Nov Student Presentations of Topic 9: Low Design / Bad Design Monday, 18 November SP14 registration begins Questions and Discussion Introduction of Topic 10: Reactionary Design / Culture Jamming Week 13 29 Nov Thanksgiving Holiday. No class. Week 14 6 Dec Student Presentations of Topic 10: Reactionary Design / Culture Jamming Questions and Discussion Final Paper Topic Determination Week 15 13 Dec Final Paper Draft Due – Individual Meetings Week 16 20 Dec Final Class – Course Wrap-up / Overview Friday, 20 December Last day of classes. Please note: The rest of the template is uniform for all PNCA classes, it includes: PNCA grading policy, statement on plagiarism, library ACE. This section should be included in any electronic versions of the syllabus, but doesn’t need to be distributed to students in paper form. ACE The Academic Center for Excellence (ACE) @PNCA is a peer driven support network for students at all levels. ACE provides in person and online assistance with the following: study skills, digital tools, research, writing and editing strategies, math, professional practices (rà ©sumà ©s, cover letters, documentation), idea generation, project management, organization, and more. For more information, location and hours, please visit the ACE Homeroom site: http://homeroom.pnca.edu/sites/1019 About Your Library The Charles Voorhies Fine Art Library provides research assistance, help with citations and bibliographies and a place to document your artwork. Whether you are looking for articles, books, audio collections, DVDs, or Web resources, the library can help! For research help contact Dan McClure ([emailprotected]) and for help with library materials contact Serenity Ibsen ([emailprotected]). More information is available at www.library.pnca.edu. Statement on Academic Integrity PNCA values intellectual honesty and encourages authentic expression, independent thinking and original writing. The College expects that all work conducted and submitted by our students shall be the combined result of original thought and ethical research. All acts of plagiarism, whether deliberate or unintentional, are considered a violation of the Student Code of Conduct and will not be tolerated on the PNCA campus. It is the student’s responsibility to be aware of and to act in accordance with the PNCA Guidelines for Academic Honesty. This is a document that defines plagiarism, discusses the conventions of ethical research and documentation, and explains the appropriate uses of source materials. These guidelines also describe the student’s responsibility for maintaining documentation and evidence of research in order to verify originality in all writing assignments at PNCA. The document: PNCA Guidelines for Academic Honesty is provided for you in the following locat ions on campus: the Student Handbook, the Library’s Homeroom site, the Academic Integrity HomeRoom site, the ACE HomeRoom site, the Foundation HomeRoom site, the Liberal Arts Homeroom site. You may also view written copies of the PNCA Guidelines for Academic Honesty in the office of Student Services, the Academic Dean’s office, and the PNCA Library. Student Information + Responsibilities Students are expected to have in their possession a current edition of the Student Handbook. Students are responsible for all the information contained in the handbook, and should refer to the handbook frequently for deadlines, policies, procedures, and responsibilities. Student Handbooks are available in the office of Student Services. Students are expected to check their student mailboxes frequently for communications from their instructors or from the administrative offices of the college. Week Two is the last week that you may add or drop a class with no penalty. Week Eight is the last week that you may withdraw from a class with a â€Å"W.† PNCA Grading Criteria This is the institutional grading policy for all PNCA students. Grades are distributed after the end of each semester. Grading Criteria Grade A: Student performance is outstanding. Student exhibits excellent achievement and craftsmanship in all aspects of work. Student exceeds the problem criteria and consistently challenges himself/herself to seek fresh solutions to assigned problems. Student exhibits a commitment to expanding ideas, vocabulary and performance. Student’s attendance, participation and class involvement are excellent. Grade B: Student performs beyond requirements of assignments. Student exhibits above-average progress and craftsmanship in all work. Student meets and exceeds the problem criteria. Student exhibits above-average interest in expanding ideas, vocabulary and performance. Student’s attendance, participation and class involvement are above average. Grade C: Student performance is average and all requirements are fulfilled. Student exhibits an average level of progress and improvement in all work. Student meets the problem criteria. Student exhibits interest in expanding ideas, vocabulary and performance. Student’s attendance, participation and class involvement are adequate. Grade D: Student performance is uneven and requirements are partially fulfilled. Student’s output is minimal. Student exhibits minimal improvement in work. Student does not meet the problem criteria in all assignments. Student exhibits minimal interest in expanding ideas, vocabulary and performance. Student’s attendance, participation and class involvement are less than adequate. Grade F: No credit earned. Student fails to meet a minimum performance level. Student does not exhibit achievement, progress or adequate levels of craftsmanship in all assignments. Student’s work is consistently incomplete or unsuccessful. Student’s attendance, participation and class involvement are inadequate. Pass/Fail Grade: A Pass/Fail grade will be given for designated courses in which the course content is such that direct faculty oversight of the learning experience is not possible, and evaluation on the present grading scale would be difficult. â€Å"Pass† implies a â€Å"C† grade or above. â€Å"Fail† implies less than a â€Å"C† grade and course work graded as â€Å"Fail† does not apply to the degree. Pass/Fail grades are not calculated in the grade point average. This grading applies to Internships. Graphic Design Co-op uses traditional letter grades. Incompletes In certain situations, a student may request an â€Å"Incomplete† grade in a class. You may petition for an â€Å"Incomplete† only if your situation meets both of these conditions: 1. An extenuating circumstance exists and it has prevented you from completing the coursework (Extenuating circumstances are illnesses, family, emergencies, etc.), 2. You are currently in good standing in the class. See the Student Handbook for more information about Grades and Incompletes.

Truth of a Free Spirit Essay -- Authors

Many writers apply experiences and thoughts into their work and express them in such a way the reader can relate. Critics would agree that Edgar Allan Poe left a unique mark as a short story writer. Author Ray Bradbury was quoted saying, â€Å"It doesn't matter what you do, so long as you change something from the way it was before you touched it into something that's like you after you take your hands away†¦Ã¢â‚¬  (Bradbury). Fiction writing was simple until Poe begins to put his twist around the world. During the terrible times that Edgar Allan Poe experienced as a young man would ultimately alter the history of short stories, he was unique and an extraordinary writer therefore exemplifying the mark that he leave upon society. In Poe’s early life, he goes through a devastating and tragic event as his mother dies and his biological father abandons him at the age of two leaving him as an orphan. Writer W.D. Johnson says, â€Å"Increased susceptibility to depression and anxiety is another result of the heightened stress levels associated with being an orphan. Typically, the younger the age of a child when orphaned and the longer he remains without a home, the more drastic the impact that his experiences as an orphan will have on his development† (Johnson). Poe’s adolescence seemed to be on a path destined for self-destruction following the Allan’s informal adoption of him at the age of two. Francis and John Allan, his foster parents, forced him to move away from his siblings in Boston to their home in Richmond, Virginia. From a young age, Poe lacked the stability of a fruitful environment for a boy to grow and mature into a man acceptable to society’s standards. Poe and his foster family moved to England in pursuit of business adventures fo... ...itical Essay)." symploke. University of Nebraska Press. 1999. HighBeam Research. 6 May. 2012 http://www.highbeam.com. Page, K.. How Maslow. N.p., 2010. Web. 4 May 2012. . Schogol, Jeff. "Why was Edgar Allan Poe kicked out of West Point? ." Stars and Stripes. Stars and Stripes, Febr. Web. 4 May 2012. http://www.stripes.com/blogs/the-rumor- doctor/the-rumor-doctor-1.104348/why-was-edgar-allan-poe-kicked-out-of-west-point- 1.133805. "Year Without a Summer." Wikipedia. Wikimedia Foundation, 05 June 2012. Web. 07 May 2012. http://en.wikipedia.org/wiki/Year_Without_a_Summer. Soon, Willie, and Steven Yaskell. "Year Without a Summer." Year Without a Summer. World Scientific Publishing Company, July 2001. Web. 07 May 2012.

Never Leave Your Past Behind Essay -- Essays Papers

Never Leave Your Past Behind I grew up in a low-income, single-parent family on the far south-side of Chicago. My sister and her family also lived with us. They needed a place to stay while they looked for a more affordable house. One thing my family doesn't do is turn our backs on each other. Sociologists who claim to be experts on non-white families have their own words for this type of situation. They derogatorily label this as a poverty-stricken, Black matriarchal extended family who lives in the ghetto. Yet all in all, we were happy because we helped each other. We were not the type of family who wondered what the next meal would be. We always knew we would have food on the table, but the type of food was a different story. Plain and simple, our goal was to survive. Survival to us was to get a job and hopefully wake up the next morning. I didn't think about college. Why should I? I didn't even like high school. But, somehow, somewhere an idea was instilled in me. "To be 'somebody,' I must go to college; if I didn't go, I would be a nobody." Because I believed this, I became more distant from my family and friends. I felt ashamed of my family because no one went to college right out of high school except for me. I felt my friends were not worthy of my time because I was in college and they were not. My biggest mistake in life was when I tried to leave my past behind me. It took me nineteen long, painful years to believe and learn never to be ashamed of who I am or where I came from. Since I lived in an area where there were only Blacks, I wanted to get away from them. I didn't want to witness another murder in front of my house. I couldn't tolerate another ten-to-twenty year old drug seller stopping me and asking, "... ... love myself and to love my family. After I knew my family supported me in whatever I did or said, my life began. Mentally, I grew stronger. I no longer felt ashamed of my family or friends. Most of all, I no longer was ashamed of being Black. In fact, I love myself because I am Black. I feel empowered because of what I have seen and experienced. I am proud because I am the first one in my family to attend college. I am happy because the people I love have helped me the best way they knew how. The only thing I needed to do was to love myself for who I am and where I came from. In order to do that, as my favorite high school teacher said, "You have to know where you came from before you know where you're going. And, you can't do that by acting like someone else." After all these years, I am proud to announce that I am a Black woman who knows where she's going.

Apollo 13 Movie Physics

Have you ever wondered what it would be like to fly in space or work on the crew at NASA that helps the astronauts get home safely? These two jobs both use many of the laws of physics. In fact, almost everything they do involves physics. Apollo 13 is a movie that epitomizes what those jobs are like and how much physics is required. The three main laws of physics in the movie were Newton’s Law of Universal Gravitation, Newton’s First Law, and Newton’s Third Law. One main law in Apollo 13 was Newton’s Law of Universal Gravitation, defined as F=Gm1m2r2, where G=6. 7? 10-11. The first main scene in which this law was needed was when NASA decided that it would be best for the crew to take a free-return trajectory back to Earth. Newton’s Law of Universal Gravitation was needed to figure out the net force and its direction on the Apollo 13 spacecraft as it followed its path. NASA made sure that Apollo 13 would make it back to Earth and not be lost in space . Another scene in which Newton’s Law of Universal Gravitation was needed was when the Apollo 13 crew needed to execute a burn.This law helped them calculate the forces acting on them by other planetary objects, and therefore how much force their burn needed to apply. By simply adding together force vectors NASA could predict the exact location at any time of the Apollo 13 spacecraft. The third scene in which this law was required was when Jim Lovell stated that they â€Å"just put Sir Isaac Newton in the driver’s seat† after NASA had ordered them to power down both the LEM and the Command Module.What Jim Lovell was stating was that since now they couldn’t do anything to control the ship the only thing guiding them to Earth were Newton’s laws, especially Newton’s Law of Universal Gravitation. If Newton’s laws were to fail then the Apollo 13 crew would have had no chance of getting home. To sum it up, three scenes in Apollo 13 that use d or showed Newton’s Law of Universal Gravitation were when Jim Lovell said that they â€Å"just put Sir Isaac Newton in the driver’s seat†, NASA decided that a free-return trajectory was the best way to bring the Apollo 13 crew back home, and when Apollo 13 needed to execute a burn to adjust its course.Another prevalent physics law in Apollo 13 was Newton’s First Law, which states that a body will persist in its state of rest or of uniform motion unless it is acted upon by an external unbalanced force. In most scenes of Apollo 13 that show the spacecraft in space this law was visually demonstrated. The Apollo 13 spacecraft was always in uniform motion unless it was acted on by another external unbalanced force. The most significant force in space that would act on the spacecraft was that of gravity.Gravity from other large masses, such as the Earth, Moon, and Sun, acted as the external unbalanced force which changed the spacecraft’s speed and dire ction. If all the gravity in space were to suddenly disappear and the net force on the spacecraft were to be zero then the Apollo 13 ship would simply adhere to its uniform motion tangent to its original path. Another group of scenes in which Newton’s First was displayed was when the astronauts moved around in their spacecraft while in space.It is quite easy to tell from watching how the astronauts moved around in 0g that they were exhibiting Newton’s First Law. If an astronaut in the movie applied a force in one direction to move in the other that astronaut would then move at a constant velocity (in relation to the ship) as soon as that force was removed. On the contrary, if no force were applied, the astronaut would remain at rest in relation to the ship. Overall, Newton’s First Law was shown in Apollo 13 when the astronauts moved around in their spacecraft and when the spacecraft traveled through space.The third law that was very important in Apollo 13 was Ne wton’s Third Law which states to every action there is an equal and opposite reaction. The first main scene in which Newton’s Third Law was demonstrated was when the Apollo 13 crew had to execute a burn. By firing the main engine, they released gas particles into space, therefore applying an equal and opposite force on the ship. The burn was used to break free of the Earth’s gravity and to adjust the spacecraft’s trajectory slightly in order to make it home.Another main scene in which Newton’s Third Law was displayed was when the astronauts were in space, and they needed to move around in their spacecraft. In order to move, the astronauts had to apply a force in one direction in order to have a reaction force applied on them in the opposite direction. In 0g the astronauts could use their hands to push on other surfaces and move them in the opposite direction. The third main scene in which Newton’s Third Law was demonstrated was when the Apol lo 13 spacecraft ejected small amounts of gases to adjust the trajectory of the ship by fine amounts.By ejecting small amounts of gases the ship was exerting a force in one direction and receiving an equal force in an opposite direction, and therefore changing its path. By releasing just the right amount of gases the spacecraft could change its trajectory to make it home safely. Looking at the whole, Newton’s Third Law was exhibited by the spacecraft when it ejected gas particles into space, when it executed a burn, and when the astronauts moved around in their spacecraft. Many laws of physics were used in the movie Apollo 13.These laws helped to enforce the realistic feeling that this movie gave to its viewers. Not only were Newton’s Laws included but others were also used in smaller quantities, including Kepler’s laws and kinematic equations. Ultimately, the three commonly used laws in Apollo 13 were Newton’s First Law, Newton’s Third Law, and Ne wton’s Law of Universal Gravitation.

A Stop Lighting up Cancer Sticks Essays

A Stop Lighting up Cancer Sticks Essays A Stop Lighting up Cancer Sticks Paper A Stop Lighting up Cancer Sticks Paper Cancer, emphysema, asthma†¦ death. What are all of those tragic health conditions associated with? No, not merely old age or even sucking on the exhaust pipe of a Buick, though the latter’s not too far from the truth. The horrific reality is that everyday, everywhere in this country, people are lighting up cancer sticks. Cigarettes, as they are more generally called, are poisoning the nation with every wheeze-filled puff that anyone draws in and exhales. Smoking cigarettes is one of this nation’s worst evils, yet is more acceptable than many less hazardous substances that are considered illegal. Cigarettes should be banned entirely from the United States because they kill not only the populace that smokes them, but innocent bystanders as well, are more addictive than marijuana or painkillers, and are produced and distributed by an industry that gains profit from millions of their customer’s deaths. Second-hand smoke warnings swarm all aspects of the media in today’s society, and with good reason. Anyone that believes they cannot be affected by smokers’ habits is tragically mistaken. So maybe a guy standing at a crosswalk doesn’t mind the fact that he’s poisoning himself, but the mother waiting behind him walking her eight-year-old son to school certainly does. They both are inhaling the toxins spewing from that Marlboro 100, and probably don’t like it. Okay smoker, it’s alright to kill yourself, but not others. Also, anyone with asthma or emphysema can have their illnesses worsened; second-hand smoke is even more perilous to them. People on the street or in the same room may be able to walk away from the smoky clouds, but what about those that can’t? Kids, infants, and even unborn children may be getting sick just from second-hand smoke in the next room, causing innumerable health risks. In fact, â€Å"After the first month of life, infants of parents who smoke have higher mortality rates through the first year of life, mostly because of an increased risk for sudden infant death syndrome and respiratory conditions like bronchiolitis† (Gidding 750). Yet, each smoker is unaware that a small part of their habit damaged the lungs of the girl that now needs constant medical supervision or the boy that looks through the fence at the kids playing baseball, but can’t join in because he’d suffer an asthma attack. If they had just put out their light†¦ But it doesn’t bother a smoker†¦ if the people exiting an airport cough when they walk out of the terminals through the â€Å"smoking areas,† what are a few kids? The second-hand smoke that kills thousands of people every year must be eliminated, and can be if the first-hand smoke is banned. Among the hundred or so chemicals tucked away inside a cancer stick is a pesky little addictive substance called nicotine. So along with urea, carbon monoxide, and methane, those who smoke get a substance more addictive than caffeine, defined by the New American Webster Handy College dictionary as, â€Å" a poisonous, colorless, oily liquid. † Sounds great, huh? Most smokers might try not to smoke if it weren’t for the fact that they are addicted to their cigs. Surprisingly, the tobacco companies know that seventy percent of smokers want to quit but can’t (Reasons). Addiction is regarded as bad in America. We spend millions of tax dollars each year to break the addictions of junkies, or to house them in our prisons if their drugs are illegal. Heroine, cocaine, and marijuana are outlawed because they kill people, and lead to more crime based on an addict’s chemical dependency. What is to stop a nicotine addict from stealing money to buy a pack when he says he, â€Å"Needs a cigarette,† but doesn’t have the cash? Maybe jail time can act as a deterrent. Addictions, especially those that are life threatening, have been the targets of countless programs to help eliminate them because our nation considers them to be appalling. An addiction to nicotine is as serious as any other drug addiction and should be dealt with accordingly, by outlawing its distribution, and the cigarettes that are its envelope to the citizen of this country. Big business is part of America and tobacco companies are some of the biggest businesses, but they make their money from the suffering of others. When anybody buys a pack of cigarettes, they are supporting a series of corporations that gain profits from dealing death to the people of America. Here’s how it works: tobacco companies lose thousands of customers each year†¦ because they die. So every day they need about 3,000 new smokers, and they look to the kids (3,000). Have those capitalists realized that it’s morally unjust to market lethal, addictive substances to kids? Yes, but as long as the money keeps rolling in, the lives of their customers don’t matter. Buying a pack of cigarettes is simply feeding the monster that is the tobacco industry. Before the lungs of a smoker are affected, their wallet is: approximately $4. 00 for a pack of twenty. Let’s do the math on that one! Twenty cents per cancer stick, a pack each day†¦ Smoking costs $1, 460 per year, but don’t worry because a bonus gift comes with that; it’s called lung cancer, or a few lucky individuals can spend almost fifteen hundred bucks a year for asthma. Tobacco companies profit from death and poor health. Being paid for thousands of murder each year doesn’t seem highly regarded or even decent, so the sale of cigarettes should be illegal. Okay, this is America, the land of the free; smokers have the freedom to smoke. It has been known unofficially as the â€Å"right to smoke† in arguments over this matter of banning cigarettes. Right to smoke? What about the right to breathe clean air? In public places, more people don’t smoke than those who do, and since there seems to be a basis on laws and rights when it comes to this issue, and this is a democracy†¦ TAA-DAA the non-smokers would win this one. God bless the rights in America! At home, in private, it’s okay to smoke though, some would think. A smoker should still have that right, right? Well, again going to the government of America and its laws, suicide is illegal. That includes poisoning; ingesting chemicals that kill the human body slowly, which seems like suicide and in a court of law, could be confirmed. When it comes to a â€Å"right to smoke,† it’s great to live in such democratic society where the people make the laws; maybe a ban on cigarettes should be next on the lists. Tobacco companies make billions of dollars and keep thousands of people employed, but to do that they distribute death cartons. They make donations to campaigns, schools, and even health care facilities. Perhaps they believe that their donations will make people blind to the fact that their product, â€Å"kills more people than AIDS, murder, suicide, fires, alcohol, and all other illegal drugs combined† (Perspectives). How could our economy survive without them? Hello! The United States of America is one of the richest and most powerful countries in the world. The national debt is way over the billion-dollar marker, so does another billion matter? U. S. allies would donate funds to stimulate the economy. Another Great Depression is not an option, and wouldn’t happen, especially since the U. S. is known for its thriving economy. As far as finding new jobs for all the tobacco company employees, well maybe some openings are available as gravediggers and morticians; they could see the error of their ways more clearly by looking at a man that died of lung cancer with a pack of Camels in his pocket. The economy of the U. S. is structured firmly so that the people back it with their money. If nothing else, $1,460 a year could be spent on something else, like shopping sprees, to help the economy for those that are worried about another stock market downfall. This nation can survive without cigarettes, and so could thousands of its citizens. Who suffers from the effects of cigarettes? Answer: the smoker, because according to Hospital Practice, smokers are admitted to hospitals twice as often as nonsmokers (Hospital 8), and anyone standing around them, including unborn children. Who benefits from smoking cigarettes? â€Å"Big Tobacco,† the heartless corporate giants that profit from death. Second-hand smoke kills, addiction runs rampant and needs to be stopped, and the tobacco companies are laughing at the suffering of consumers all the way to the bank. Such an illegitimate situation can be easily avoided. Ban the cancer sticks; ban the self-poisoning. Eliminate cigarettes†¦ eliminate the problem. Bibliography : WORKS CITED 3,000 New Customers. 6 Jan. 1989. The Journal of the American Medical Association. 16 Jan. 2002 . Gidding, S. S. and M. Schydlower. Active and Passive Tobacco Exposure: A Serious Pediatric Health Problem. Pediatrics 94 (1994): 750-51. Hospital Practice 15 Jun. 1997: 8. â€Å"Perspectives in Disease Prevention and Health Promotion: Smoking – Attributable Mortality and Years of Life Lost. † Morbidity and Mortality Weekly Report 46. 20 (1997): 444. Reasons for Tobacco Use and Symptoms of Nicotine Withdrawal Among Adolescent and Young Adult Tobacco Users. 21 Oct. 1994. Center for Disease Control and Prevention. 19 Jan. 2002 ythaddct. htm.

DNA Technology essays

DNA Technology essays DNA (deoxyribonucleic acid) is a very important part of our lives today. It is found in the nucleus of cells on the chromosomes. It is found in many cell organelles, such as plasmids in bacteria, chloroplasts in plants, and mitochondria in both plants and animals. DNA helps us to perform many actions in solving crimes, doing paternity tests, and also helps us to do scientific studies that were not possible until the middle 1900s. DNA has been one of the most popular subjects of study ever since it was discovered. Scientists James Watson and Francis Crick first discovered DNA in 1953. On April 2, they published a journal article that was only one page in length, but has changed the life of everyone forever. Watson and Crick claimed that DNA is made of two chains of nucleotides joined together by the nitrogen bases. The bases hold the two nucleotides together because they are complementary of each other, or ones base determines the others base. The four bases are: adenine, guanine, thymine, and cytosine. Adenine pairs with thymine, and guanine pairs with cytosine. DNA is also in the shape of a double helix, or twisted ladder. DNA has two specific functions. It provides for protein synthesis and for the growth and development of an organism. It also furnishes all descendants of the organism with protein-synthesizing information by replicating itself and passing a copy to each offspring. This information, known as the genetic code, lies in the sequence of bases of DNA, which specifies the sequence of amino acids in a protein. DNA does not act directly in the process of protein synthesis. Instead it acts through the formation of a particular type of RNA called messenger RNA. The DNA technology that we have today is an extremely important part of scientific research today. Without the knowledge we have about it we could not do such applications as: paternity tests, solving crimes and other cases, and etc. Geneticis...

How to Become More Fun If You Think Youre a Boring Person

How to Become More Fun If You Think Youre a Boring Person In this post we’re going to go through a 5 step process that can quickly turn even the most boring person into a real lively individual. No kidding. We start by tackling your self-identity and then move on to your mortality and chasing fears with a big fat smile on your face. Sound fun? Yeah, that’s part of it. Let’s begin! 1. Step Outside Your Old Personal Narrative This is one of those quotes we all need to write down somewhere and look at regularly until we memorize it. If you want, just read it aloud ten times in a row and chances are you’ll never forget it (the beauty of propaganda): â€Å"I’m not what I think I am. I’m not what they think I am. I’m what I think that they think I am.† Get it? Keep reading it until you do and once that light bulb goes on above your head your life will instantly change. You’ll then realize you can be†¦anyone you choose†¦anytime you choose. Your old personal narrative is the elevator pitch you tell yourself when opportunity comes knocking that keeps you cocooned in a comfort bubble. You are not your past. You are not your future. You are right now. That’s it. That’s all you ever get at once. And, you can begin creating a new self-story as soon as you decide you’re good and ready. If it’s â€Å"I’m an incredibly fun person to be around† and you believe†¦it shall be so. 2. Add Some Spontaneity It’s pretty funny when you think about it, trying to be spontaneous. Here’s the deal, every single day of your life (when you’re not cave dwelling in your room) you’re confronted with tons of choices. Some more spontaneous than others. Those are typically the ones your old personal narrative tries to keep you away from (because they change who you are). Decide to be more spontaneous from this point forward. Decide that you’re going to become an amateur yes-man/woman and start chasing down those spontaneous leads that life keeps giving you. Sometimes just one is all you need to begin down a completely new path. 3. Remind Yourself of Your Mortality Often This always helps. Remember, you’re going to die someday. Really drink that in. Not just in a passing scared kind of way but a completely open and honest acceptance. Your life is going to end. You will one day cease to be and nothing you do or don’t do can change that fact. Period. Well, unless you opt to become a robot or something. But anyways, the next time you feel like a boring person living a boring life, remind yourself that you have a few figurative moments left to take advantage of. 4. Make Your Goals More Fun Maybe your goals are boring? Maybe your vision of the future and what you’re working towards are drab, generic and uninteresting. Not to say they aren’t awesome and great and all that, but perhaps they could use some freshening up around the rough edges? It’s hard to be a fun person when you lead a boring day to day routine. Start adding in the fun to your goals: relationships, business, education, etc. 5. Chase Your Fears Smile Even though this is step 5, these are probably two of the easiest things to understand and do. First, you chase your fears. What are you afraid of? I mean honestly. Are you afraid of success and popularity? Are you afraid of being liked by people? Are you afraid of being well-known or exposed? Once you write out this bucket list of fears, begin to chase them down (within reason, no burying yourself alive or anything). You get the idea. If you’re afraid of heights, go sky diving. Now, the second part is subtle. SMILE! Because we have no idea how we are perceived by others (see step 1), and because we have no idea what we look like while we live our lives, we really don’t take too much notice of the look on our face throughout the day. I tell you this, if you smiled 30% more for the next week you would notice an improvement immediately. Never, ever, EVER, underestimate the power of smiling. We’re drawn to it. Our minds love it. We want to smile more, whether we know it or not. Chase those fears of yours with a smile on your face, sporting fun goals, a new personal elevator pitch and a new sense of spontaneity. Cool? We’d like to hear back from you on this. What do you think?

Supply and Demand Simulation Assignment Research Paper

Supply and Demand Simulation Assignment - Research Paper Example The shift in the demand curve in the simulation may take place because of any determinant other than price; therefore, there may be a shift in the demand curve due to the availability of a supermarket or grocery store near the apartment because if people are not able to find a store for daily needs near to their homes, that would not encourage them to buy the apartment. Furthermore, if there is a change in the prices or the quality of the Oakridge Builders’ homes, then the consumers may buy those and not the Goodlife apartments. This shift would reduce the number of homes being sold to families and thus the curve would go below the equilibrium price level. The supply curve would mostly shift due to a technological innovation and thus if the Company is able to bring about some technological innovation in their homes, that is, make them more digitalized, have proper security systems inserted then consumers will be interested in purchasing them. This shift will cause an increase in the supply of homes to consumers and thus result in going above the equilibrium price level due to the want of more homes by consumers and possible lack of the equal amount of supply. From the simulation the supply and demand can be understood as follows; taking products made by Apple and Microsoft, they may be similar in terms of usage however are different in terms of technological innovation. In the same way, Goodlife apartments appeal to families more than the retail homes from Oakbridge thus providing a clear competition for Goodlife to dominate the market just like Apple does even though it produces more expensive products, but it has a certain unique selling price. The concepts of microeconomics help in understanding the factors that affect supply and demand shifts on the equilibrium price and quantity as they talk about the shifts on an individual level; for example, if in a household, an individual had to choose between buying tea or coffee as a preferred beverage, the p rices of the same would affect his personal choice. Furthermore, if there was a shortage of supply of one of them, he would go for the other and similarly, if there was an increase in the price of one, he would choose the other as a substitute. This would affect the demand and supply curves to move up and down affecting the equilibrium price levels as per the quantities. The concepts of macroeconomics on the other hand refer to an aggregate demand and aggregate supply which takes place on a market level taking into account the personal needs and choices of all the consumers in a given area. Thus, from the point of view of households as well as firms, the factors that affects the shifts in demand and supply curves in macroeconomics may be understood by looking at the aggregate equilibrium price and quantity levels. Price elasticity helps in understanding how an individual’s demand can be lowered or increased by fixing a certain price for a particular commodity. As seen in the simulation, when the prices for the apartments are lowered, the demand for the same will be higher. At a higher price however, the demand will remain consistent for the group of people belonging to the category that can afford the apartment. At this point, the supply of the number of apartments is not taken into consideration to determine where the price of a single apartment will be set. The main

Capital Punishments Essay Example | Topics and Well Written Essays - 750 words

Capital Punishments - Essay Example In a wider context, capital punishment demeans human dignity. Violence cannot solve the rising cases of criminality. It should be stressed that toleration of execution as a means to solve criminality leaves an imprint on the citizenry’s mind that violence should be confronted with violence (Fridell 33). Capital punishment acts to legitimize violence within society. For this and other reasons to be discussed in this paper, capital punishment should be abolished since it is degrading to human life value. There are those in society who perceive capital punishments as beneficial to human society due to its ability to deter criminals from committing crimes. In addition, they believe that capital punishment ensures that violent criminals have no chance to dish violence on society (Melusky & Pesto 55). However, it is important to note that these arguments have no support in the form of scientific literature. There is no proof that a causal connection exists between criminals committi ng crimes and capital punishment. In addition, empirical research proves that many crimes committed in the US are crimes of passion or unplanned or un-premeditated crimes. Logically, when crimes are committed when a person is angry, the idea of capital punishment will not deter the prospective criminal at the time he is about to commit the crime (Melusky & Pesto 56). This is because he cannot rationally calculate the merits and demerits of his/her actions. Capital punishment can lead to wrongful execution and, therefore, must be done away with. For example, the case of Randall Adams in Texas had seen him sentenced to death for a crime he had not committed. According to Errol Morris, whose documentary led to his freeing, â€Å"Prosecutors sometimes push capital punishment cases to improve their CV† (Morris 1). Unfortunately, in other cases, the evidence that can prove the death row inmate’s innocence is only obtained following their execution. Therefore, because there i s the ever present chance of wrongful execution, capital punishment should be abolished. Capital punishment creates doubt in society that the justice system is unreliable when they really need it. It also emotionally hurts the families of people who have been executed wrongly because it is impossible to resurrect them. Because judges and juries are humans and can make wrong decisions with regards to those deserving acquittal or conviction, wrongful executions will always occur (Melusky & Pesto 57). For this reason, capital punishment, because of its irreversibility, must be abolished. Another detrimental effect of the death penalty has to do with the fact that it sends a message to society that their justice system acts as a revenge advocate, especially for those people who are victimized because of heinous crimes (Mandery 18). The death penalty sends a message to society that the reason the justice system exists is to aid the victims of heinous crimes and their families, rather tha n determine whether the suspects in the crime are guilty or innocent. Capital punishment can be interpreted in another way, which is that it does not give the offender any chance to realize their mistake and act to correct it. The American justice system, in this case, is made to look biased and partial when it uses capital punishmen

Religion in school Essay Example | Topics and Well Written Essays - 750 words

Religion in school - Essay Example This has led to wide spread ignorance in terms of one own religion as well as the religion of the worlds. In the global village of today where we reside, it is important to know the basics of the main religions in the world in order to be able to relate to the people of a different faith. The disappearance of religious studies in schools has led to deterioration of moral and ethics in the general society. By being taught ones own religion as well as the different religions of the world in school; the children tend to develop awareness, patience and tolerance amongst themselves and towards people of different race, ethnicity and religion. However due to the deterioration of morality caused in the society because of lack of religious education the children are now depicting lower tolerance towards different groups and races in their school. This has resulted in a substantial increase in the race hate crimes and racial, as well as ethnicity basses harassment in schools. â€Å"The number of reported xenophobic, anti-Semitic, and homophobic crimes has increased considerably between 1997 and 2003. The most common hate crimes against immigrants are threats, harassment, slander, ethnic agitation, and assault.† (Bunar, 2007) The other problem that is caused by lack of religious education is the increase in the violence and the number of shootings in the schools. The trend for high school shootings by children against their teachings and peers has shown an alarming increasing trend since the shootings of 1996. One of the most prominent ones was the high school shooting in Cleveland in the Succes Tech Academy. In this shooting â€Å"14-year-old Asa Coon wounded two teachers and two students before killing himself. One of the teachers, Michael Grassie, had already realized that Coon needed special attention. Coon had been singled out as a troubled youth after being disciplined for fighting.† (Raymond, 2007) In order to

Systems Dvelopment Case Study Essay Example | Topics and Well Written Essays - 500 words

Systems Dvelopment Case Study - Essay Example The system also provided the factor of motivation that it was able to identify the cost saving opportunities and prospects for the Pepsi Company. The billing management offered by the project also served as a motivating factor for the company to implement the system. BusinessObjects Corporation was one of the participants involved in the development of the Purchase to Pay System. It was involved for the providence of business intelligence information to Pepsi Co. and also for the storage of the procurement in a well managed and efficient database. The systems development life cycle approach which can be best applied to the Purchase to Pay System of the Pepsi Co. was the iterative approach. Through this approach the prototype of the new project that was to be implemented should be designed for the convenience of the staff of Pepsi and also for the ease of use and should be improved through a number of iterations. For achieving the best system development, the system is improved through iterations in the prototype in this approach. This kind of approach would be helpful for Pepsi to get the best out of the Procurement System that it planned to implement in the company. 5. Assuming that you were responsible for designing and implementing the new procurement system at PepsiCo, what problems and opportunities would you have considered in conducting your initial systems investigation The purcha

PORTFOLIO ASSIGNMENT Essay Example | Topics and Well Written Essays - 1000 words

PORTFOLIO ASSIGNMENT - Essay Example The article defines the adolescent depression as a disorder that affects teenagers. According to the author, such a disorder mostly leads to sadness, a loss of self-worth and interest in the activities and discouragement. It further elaborates the different causes and symptoms of depression in teens. Some of these symptoms are loss of but sometimes an increase in appetite, loss of concentration, decision making, fatigue, feeling upset, restless, and irritable, worthless, hopeless, self-hatred, thinking or talking about suicide or death and trouble sleeping. If the behavior of a teenager changes for more than the period of two weeks, then it is also considered as a symptom of depression. True depression in teens in most of the cases is difficult to diagnose, therefore the author emphasizes to gather the information from friend and family members to identify depression in teenagers. This article doesn’t only throw light on the medication and therapy for treating the depression b ut it also considers the possible complications and prevention techniques. (Berger) Depression can be a response to many situations factors and stresses. However, the author argues that in teenagers, depressed mood is common because of the normal process of maturing, the influence of sex hormones and independence or more freedom conflicts with parents. It may be cause of death of a friend or relative, a breakup with a boyfriend or girlfriend and failure or poor grades at school. The author considers two mains factors that contribute to the depression in teens, the hormones and social pressures. By explaining the biological and hormonal causes of the problem, the article takes into account the epigenetic approach and by throwing light on the school performance and environmental stress the author takes a socio-cultural approach to this problem. However, the author did not approach this problem on the basis of other theories

Systems Dvelopment Case Study Essay Example | Topics and Well Written Essays - 500 words

Systems Dvelopment Case Study - Essay Example The system also provided the factor of motivation that it was able to identify the cost saving opportunities and prospects for the Pepsi Company. The billing management offered by the project also served as a motivating factor for the company to implement the system. BusinessObjects Corporation was one of the participants involved in the development of the Purchase to Pay System. It was involved for the providence of business intelligence information to Pepsi Co. and also for the storage of the procurement in a well managed and efficient database. The systems development life cycle approach which can be best applied to the Purchase to Pay System of the Pepsi Co. was the iterative approach. Through this approach the prototype of the new project that was to be implemented should be designed for the convenience of the staff of Pepsi and also for the ease of use and should be improved through a number of iterations. For achieving the best system development, the system is improved through iterations in the prototype in this approach. This kind of approach would be helpful for Pepsi to get the best out of the Procurement System that it planned to implement in the company. 5. Assuming that you were responsible for designing and implementing the new procurement system at PepsiCo, what problems and opportunities would you have considered in conducting your initial systems investigation The purcha

Sexual Orientation Essay Example | Topics and Well Written Essays - 500 words

Sexual Orientation - Essay Example The legal rights of homosexual couples is often the first subject touched upon in the argument for the legalization of gay marriage. The Fourteenth Amendment of the United States Constitution declares that states are prohibited from altering the privileges and rights of American citizens, including marriage (Walzer 56). When individual states attempt to make gay marriage illegal, they go against this amendment; these states deny rights based on sexual orientation, which is prohibited by the Constitution. As such, many states have offered homosexual couples the opportunity to join in civil unions, legal bindings that are similar to marriage, though they often do not come with the same perks, such as adoption or aspects pertaining to financial security. According to people that are against gay marriage, the institution of marriage can only be between a man and a woman. Most people back this up with religions and biblical scriptures, claiming that it simply is not right for a same-sex c ouple to be romantically involved with each other (Fejes 217). Due to this, it is considered to be a sin for a homosexual couple to exist, let alone for the couple to become married.

The many hardships of society Essay Example for Free

The many hardships of society Essay Victor does not show love and domestic affection to the creature after he has given it life he just abandons it without some one to look after it and care for it as Victors family has done. Unable to endure the aspect of the being I had created I rushed out of the room and continued along time traversing my bedchamber. Victor does not show any love for the creature he has created. He is unable to endure this gives the reader the image that the creature has become so ugly. Even though he has collected the body parts from beautiful people the creature is still hideous. This shows a complete lack of love and domestic affection that has been shown to Victor in abundance by his parents. Victors parents show that there is a strong family bond between them and their son. I was there playing their idol, and something better than their child, the innocent and helpless creature bestowed on them by heaven. In this paragraph Victor describes himself as their plaything their idol. Him and his parents are inseparable and they looked up to Victor although he is a small child. They wanted him to be safe and happy. Victor is also described as small and innocent helpless creature. Victor does not show the same affection for the creature. I beheld the wretch- the miserable monster whom I created. Victor describes the creature as a wretch, this shows that Victor as a young child was shown love and affection but he is now incapable of showing the same love that was shown to him by his parent to the creature the baby that he has created. These adjectives describe the monster as physically ugly this is one of the reasons why victor rejects him, because he wanted to make a beautiful creature. Victor is also described as helpless and innocent and that he cannot fend for himself and he needs an older figure to be responsible for his actions and to keep him safe. Victor abandons the creature as soon as he realizes that he has made a mistake in trying to play god. But what has he abandoned he has abandoned a young inexperience, defenseless, innocent helpless creature. So again we see Victor being shown great love and domestic affection by his family. But when he grows up he is unable to show the same love and domestic affection towards the creature. Victor is brought up in a protective bubble when he is younger. I was so guided by a silken cord that all seemed but one train of enjoyment for me. Using the word silken cord refers to the umbilical cord that gives the entire growing child what it needs to survive. This is directly linked to Victor parents and the fact that they are providing him with so much love and domestic affection that he does not have to do anything he does not have to fend for himself. This Silken cord of tender love and affection is not there when the creature is brought to life. He has to learn to find his own way because he is an outcast of society so he would find it hard to fit in. He is on his own because victor has not got the mental strength to own up and shows this creation to the rest of the world. He also does not want to show any affection or love to this creature because he finds it physically repulsive. Victor is shown the way by his Parents they are always making decisions for him even as a young adult. When I was seventeen my parents resolved that I should become a student at he university of Inglostadt. He still has a protective bubble around him even though he is seventeen. This shows that his parents are still making choices for him that can provide him happiness or sorrow in the years to come. The creature is deprived of this from victor this is shown, as he does not know about the dangers of fire. The creature is attracted to the warmth of the fire and it is like the tender warm love that he is not receiving. I thrust my hand into the live embers but draw it quickly out again crying in pain. The creature has had no guidance from victor or anybody of higher intelligence than himself. This is why he burns his hand on the fire. If victor was about to do that either his Mother or Father would have stopped him from burning himself because they want to protecting him so he does not get harmed mentally or Physically. The creature then goes off in search of another family or someone who can nurture him properly. He finds a village he is curious to see this type pf village with cottages, which he has never seen before. Shortly after entering the village he is confronted by a mob throwing stones and various items at him. The creature is amazed at how polite and loving the people he is observing are. There gentle manners and beauty of these cottagers greatly endured me. He means that he is amazed that even though they are so poor they are still happy and show great love and affection for each other and he wants to become apart of that family. He observes the family and notices a new addition to the family called safie she is from a distant country. This gives the creature hope that maybe he may be able to be accepted into the family as safie is an outsider and she has been accepted. The creature then finds out how ugly he is and starts to doubt his reasons for being in the world. I had admired the perfect form of my cottagers- their grace, beauty, and delicate complexions; but how was I terrified when I viewed myself in a transparent pool! At first I stared back, unable to believe that indeed I who was reflected in the mirror; and when I became fully convinced that I was in reality the monster that I am. He realizes that he is a monster and that he would never fit in if he wanted to have a family that loved him and nurtured him. He starts to realize that this is the end for his hopes of a normal life. The creature tries to be accepted into the family by speaking to the blind man, the blind man is oblivious to any faults the creature may have. Agatha fainted, and safie unable to attend his friend rushed out of the cottage. Felix darted forward and with a supernatural force tore me from his father, to whose knees I clung; in a transport of fury, he dashed me to the ground with a stick . I could have torn him limb form limb, as a lion rends the antelope. He now realizes that all hope is lost of ever finding a family that will love him and show him domestic affection and so wallows in self pity. He then burns down the delaceys house at it is a symbol of a nice warm family that he is not apart of so he destroys it. Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Mary Shelley section.

Polymerase Chain Reaction (PCR) Steps

Polymerase Chain Reaction (PCR) Steps We owe the discovery of the polymerase chain reaction to Kary B Mullis in the year 1983. He was the actual proponent of PCR. Few people are aware that in 1971, Kleppe and the Nobel laureate Gobind Khorana published studies including a description of techniques that are now known to be the basis for nucleic acid replication. However, it is unfortunate that Kleppe and Khorana were ahead of their times. Oligonucleotide synthesis wasnt as simple as it is today; genes had not been sequenced and the idea of thermostable DNA polymerases had not been described. Hence, the credit for discovering the PCR remains with Kary Mullis. The Polymerase Chain Reaction is essentially a cell-free method of DNA and RNA cloning. The DNA or RNA is isolated from the cell and replicated upto a million times. At the end, what you get is a greatly amplified fragment of DNA. The PCR is quick, reliable and sensitive and its variations have made it the basis of genetic testing. WHAT KARY B MULLIS SAYS ABOUT HOW HE DISCOVERED THE POLYMERASE CHAIN REACTION I was just driving and thinking about ideas and suddenly I saw it. I saw the polymerase chain reaction as clear as if it were up on a blackboard inside my head, so I pulled over and started scribbling. A chemist friend of his was asleep in the car. Mullis says that Jennifer objected groggily to the delay and the light, but I exclaimed I had discovered something fantastic. Unimpressed, she went back to sleep. Mullis kept scribbling calculations, right there in the car. He convinced the small California biotech company, Cetus, he was working for at that time, that he was up to something big. They finally listened. They sold the patent of PCR to Hoffman-LaRoche for a staggering $300 million the maximum amount of money ever paid for a patent. Mullis meanwhile received a $10,000 bonus. BASIS OF THE METHOD The purpose of PCR is to generate a huge number of copies of a segment of DNA, which could be a gene, a portion of a gene, or an intronic region. There are three major steps in a PCR, which are repeated for 30 or 40 cycles. This is done on an automated cycler, which can either heat or cool the tubes containing the reaction mixture, as required, in a very short period of time. There are three major steps in a PCR, which are repeated for 30 or 40 cycles. DenaturationDuring this process, the double stranded DNA melts and opens to form single stranded DNA. All enzymatic reactions, such as those carried over from a previous cycle, stop. This will be explained in the next paragraph. The temperature for denaturation is not fixed but it usually occurs at about 95 °C. It is important to realize that the denaturation temperature is largely dependent on G:C (guanine:cytosine) content of the DNA fragment to be analyzed. This is reasonable when one considers that the G:C bond is a triple hydrogen bond and the AT bond is a double bond. Logic dictates that a triple bond should be 1.5 times harder to break than a double bond. Therefore, when the segment of DNA to be analyzed has a very high G:C content, the denaturation temperature can reach even upto 99 °C. AnnealingThis requires temperatures lower than those required for denaturation. In this process, the primers anneal to that very specific segment of DNA that is to be amplified. The primers are jiggling around, caused by the Brownian motion. Ionic bonds are constantly formed and broken between the single stranded primer and the single stranded template. The more stable bonds last a little bit longer (primers that fit exactly) and on that little piece of what is now double stranded DNA (template and primer); the polymerase can attach and starts copying the template. Once there are a few bases built in, the ionic bond is so strong between the template and the primer, that it does not break anymore. ExtensionThis is done at 72 °C. This is the ideal temperature for working with polymerase. The primers, which are complementary to the template, already have a strong ionic attraction to the template. This force is stronger than the forces breaking these attractions i.e. the high temperature. Primers that are on positions with no exact match (non complementary) get loose again (because of the higher temperature) and dont give an extension of the fragment. The nucleotide bases are added from the 5 end to the 3 end. The phosphate group of the dNTPs is coupled with the hydroxyl group of the extending DNA strand. The extension time depends on two factors; the type of polymerase used and the length of the DNA fragment to be amplified. Usually, Taq polymerase adds dNTPs at the rate of about 1000 bases per minute. It is important to realize that each component of the PCR including the input DNA, the oligonucleotide primers, the thermostable polymerase, the buffer and the cycling parameters has a profound impact on the sensitivity, specificity and fidelity of the reaction. The three steps of the first cycle are shown, that is, denaturation, annealing and extension. At the end of the first cycle, two strands have been synthesized. At the end of the second cycle, four strands have been synthesized (the three steps of the cycle have not been shown). At the end of the third cycle, eight strands have been synthesized. The number of strands increases exponentially with each cycle. Nuggets The Polymerase Chain Reaction is essentially a cell-free method of cloning DNA and RNA. There are three steps involved in every cycle; these are denaturation, annealing and extension. At the end of each cycle, the DNA doubles. Therefore, theoretically, if there are n cycles in a reaction, the number of DNA fragments at the end of the reaction will be 2n. COMPONENTS OF THE POLYMERASE CHAIN REACTION The components that are essential for a successful PCR are elaborated here. TEMPLATE DNA This is that portion of the DNA/gene that is to be amplified. Usually the concentration is  100 ng genomic DNA per PCR reaction. However, this can vary depending on the target gene concentration and the source of DNA. The PCR reaction is inherently sensitive. It is not necessary for the template DNA to be abundant or highly purified. Higher amounts of template DNA can increase the yield of nonspecific PCR products, but if the fidelity of the reaction is crucial, one should limit both template DNA quantities as well as the number of PCR cycles. DNA in solution may contain a large number of contaminants. These contaminants may inhibit the PCR. Some of these reagents are phenol, EDTA, and proteinase K, which can inhibit Taq DNA polymerase. However, isopropanol precipitation of DNA and washing of DNA pellets with 70% ethanol is usually effective in removing traces of contaminants from the DNA sample. Effects of Fixation This is of particular interest to the pathologist since he has to deal with formalin fixed tissue. DNA extracted from fresh tissue or cell suspensions forms an optimal template for PCR. The tissue is best stored at -70 °C at which the nucleic acids can be stored indefinitely. A temperature of -20 °C is sufficient to preserve the DNA for several months and at 4 °C, the DNA can be stored for several weeks. At room temperature, the DNA has been successfully stored for hours to days; however, mitochondrial DNA is very sensitive to temperature and may degrade in thawed tissues. DNA extracted from fixed tissue has been used successfully for PCR. The type of fixative and the duration of fixation are of critical importance. Non crosslinking fixatives like ethanol provide the best DNA. Formaldehyde is variable in its DNA yield. Carnoys, Zenkers and Bouins are poor fixatives as far as DNA preservation is concerned. Not surprisingly, formaldehyde is the fixative which has been evaluated the most, because it is more commonly used worldwide. The studies have demonstrated that a successful PCR depends on the protocol to extract the DNA and the length of fixation. Formaldehyde reacts with DNA and proteins to form labile hydroxymethyl intermediates which give rise to a mixture of end products which include DNA-DNA and DNA-protein adducts. Purification of DNA from formalin fixed tissue, therefore, includes heating to reverse the hydroxymethyl additions and treatment with a proteinase to hydrolyze the covalently linked proteins. However, there is no way to reverse the DNA-DNA links and these links inhibit the DNA polymerases. This accounts for the low PCR yield which is seen with formalin fixed tissue. Usually, the PCR reaction with formalin fixed DNA as a template yields products which are not more than 600 bp in size. Nuggets Template DNA is required in a concentration of 100ng for each PCR reaction. Contaminants in DNA may inhibit the reaction. Fixation of tissues provides DNA which is not as good as DNA obtained from fresh/ frozen tissues. Different fixatives give different DNA yields. Alcohol is the best fixative and Carnoys, Zenkers and Bouins are poor fixatives as far as DNA preservation is concerned. Formalin is intermediate in DNA yield. Purification of DNA from formalin fixed tissue involves heating to reverse the attachment of hydroxymethyl intermediates and treatment with a proteinase to hydrolyze the covalently linked proteins. The DNA obtained after fixation can be used for reactions in which the PCR product is not more than 600 bp. PCR BUFFER The purpose of using buffers in PCR is to provide optimum pH and potassium ion concentration for the DNA polymerase enzyme (usually obtained from bacteria Thermus aquaticus) to function. Most buffers are available in a 10X concentration and require dilution before use. Although most protocols recommend the final buffer concentration of 1X, a concentration of 1.5X might result in increased PCR product yield. The PCR buffer contains many components. Some important ones are discussed here: Divalent and monovalent cations These are required by all thermostable DNA polymerases. Mg2+ is the divalent cation that is usually present in most of the PCR buffers. Some polymerases also work with buffers containing Mn2+. Calcium containing buffers are ineffective and therefore, rarely used. Buffers can be divided into first and second generation buffers on the basis of their ionic component. The second generation buffers, as opposed to first generation buffers, also contain (NH4)2SO4 and permit consistent PCR product yield and specificity over a wide range of magnesium concentration (1.0 to 4.0 mM MgCl2). The overall specificity and yield of PCR products is better with second generation buffers, as compared with first generation PCR buffers. Buffers also contain KCl. Salts like KCl and NaCl may help to facilitate primer annealing, but concentration of 50 mM will inhibit Taq polymerase activity. Interactions between K+ and NH4+ allow specific primer hybridization over a broad ran ge of temperatures. Magnesium is one of the most important components of the buffer. Mg2+ ions form a soluble complex with dNTPs which is essential for dNTP incorporation; they also stimulate polymerase activity and influence the annealing efficiency of primer to template DNA. The concentration of MgCl2 can have a dramatic effect on the specificity and yield of PCR products. Optimal concentration of MgCl2 is between 1.0 to 1.5 mM for most reactions. Low MgCl2 concentration helps to eliminate non-specific priming and formation of background PCR products. This is desirable when fidelity of DNA synthesis is critical. At the same time, however, too few Mg2+ ions can result in low yield of PCR products. High MgCl2 concentration helps to stabilize interaction of the primers with their intended template, but can also result in nonspecific binding and formation of non specific PCR products. It is important to be aware that many PCR buffers (often sold in 10X stocks) already contain some amo unt of MgCl2. Therefore, the addition of further amounts must be carefully monitored. In the best possible scenario, the PCR would work well with the amount of Mg2+ already present in the buffer solution. However, if this does not occur, it is necessary to standardize the amount of Mg2+ in the reaction mix. This can be difficult because the dNTPs and the oligonucleotide primers bind to Mg2+. Therefore, the molar concentration of Mg2+ must exceed the molar concentration of the phosphate groups contributed by dNTPs and the primers. As a rule of thumb, the magnesium concentration in the reaction mixture is generally 0.5 to 2.5 mM greater than the concentration of dNTPs. The optimal concentration of Mg2+ should, therefore, be standardized for each reaction. Tris-Cl The concentration of tris-Cl is adjusted so that the pH of the reaction mixture is maintained between 8.3 and 8.8 at room temperature. In standard PCR reactions, it is usually present in a concentration of 10mM. When incubated at 72 °C which is the temperature for extension, the pH of the reaction mixture falls by more than a full unit, producing a buffer whose pH is 7.2. Other components Some buffers also contain components like BSA (Bovine serum albumin) and DMSO (dimethyl sulphoxide). BSA reduces the amount of template sticking to the side of the tube, making it available for amplification and reducing the risk of primer dimer. Primer dimers are products obtained when the primers anneal to each other instead to to the template DNA. DMSO has been shown to facilitate DNA strand separation (in GC rich difficult secondary structures) because it disrupts base pairing and has been shown to improve PCR efficiency. In effect, it is wise not to tamper with the buffer provided with the Taq polymerase. The buffer is usually standardized for the vial of Taq and there is no need to add additional MgCl2 or stabilizers like DMSO and BSA. However, some Taq buffers come with the buffer in one vial and MgCl2 in a separate vial. Under such circumstances, it is advisable to start with 1 µL of MgCl2 and increase its concentration in aliquots of 0.5  µL, if the initial reaction fails. Nuggets The PCR buffer contains divalent and monovalent cations, Tris Cl and other components. The PCR buffer is used to give the correct pH and potassium concentration for the DNA polymerase to function. The most common divalent ion used is magnesium in the form of MgCl2. MgCl2 concentration is vital for PCR. Tris Cl is used to maintain the pH between 8.3 and 8.8 at room temperature. Salts like NaCl and KCl may facilitate primer annealing Other components like BSA and DMSO help to increase the sensitivity and specificity of the reaction. OLIGONUCLEOTIDE PRIMERS What are Oligonucleotide Primers? PCR primers are short fragments of single stranded DNA (17-30 nucleotides in length) that are complementary to DNA sequences that flank the target region of interest. The purpose of PCR primers is to provide a free 3-OH group to which the DNA polymerase can add dNTPs. There are two primers used in the reaction. The forward primer anneals to the DNA minus strand and directs synthesis in a 5 to 3 direction. The sequence of primers is always represented in a 5 to a 3 direction. The reverse primer anneals to the other strand of the DNA. How to design a primer? The predominant goal kept in mind while designing a primer is specificity. Each member of the primer must anneal in a stable fashion to its target sequence in the template DNA. The longer the primer, the higher is its specificity. Unfortunately, the longer the primer, the less likely it is to anneal to a particular sequence in the template DNA. Conversely, if the primer length is small, it is likely to anneal, but its specificity will be poor. A compromise is reached by designing primers between 20 and 25 nucleotides long. Inclusion of less than 17 nucleotides often leads to non specific annealing, while presence of more than 25 nucleotides may not allow annealing to occur at all. Remember that the DNA sequence in the human genome appears to be a random sequence of nucleotides. When designing primers, it is important to calculate the probability that a sequence exactly complementary to a string of nucleotides in the human genome will occur by chance. Several formulae are designed to calculate such probabilities. However, mathematical expressions are not necessarily correct and in this case, the predictions maybe wildly wrong. The distribution of codons is non random with repetitive DNA sequences and gene families. It is advisable to use primers longer than the statistically indicated minimum. It is also advisable to scan DNA databases to check if the proposed sequence occurs only in the desired gene. For a practicing pathologist, it is best not to attempt designing of primers. What a pathologist requires is the primer sequence for an established test. If, for example, a pathologist requires primer sequence for the diagnosis of sickle cell anemia, all he has to do is search the web for papers related to molecular testing of sickle cell anemia. The primer sequences will be provided in the paper. Custom made primers can be commercially synthesized. Several biotechnology companies provide this facility. Before the primers are ordered, it is essential to check that the sequence is correct and that there are no missing nucleotides in the sequence. That is where, BLAST is invaluable. Before the intricacies of the BLAST search are elaborated upon, it is necessary to mention that designing a primer does not depend only on the sequence of nucleotides. Other factors like the GC content and melting point are also important considerations. They will be dealt with later in the chapter. BLAST and its uses BLAST is an acronym for Basic Local Alignment Search Tool. It is an algorithm comparing information about primary biological sequences with a library or database of sequences. A BLAST can be performed for different organisms, but in this book, we will concern ourselves with nucleotide BLAST in humans only. BLAST searches the database for sequences similar to the sequence of interest (the query sequence) by using a 2-step approach. The basic concept is that the higher the number of similar segments between two sequences, and the longer the length of similar segments, the less divergent the sequences are, and therefore, likely to be more genetically related (homologous). Before perfoming a BLAST search the oligonucleotide sequence is first identified. The sequence is fed into the programme. BLAST first searches for short regions of a given length called words (W). It then searches for substrings which are compared to the query sequence. The program then aligns with sequences in the database (target sequences), using a substitution matrix. For every pair of sequences (query and target) that have a word or words in common, BLAST extends the search in both directions to find alignments that score greater (are more similar) than a certain score threshold (S). These alignments are called high scoring pairs or HSPs; the maximal scoring HSPs are called maximum segment pairs (MSPs). The BLAST search as outlined in fig 7.2 shows the results of the search. If we scroll down further, we can see the sequences producing significant alignments. Note that in this BLAST search, there are 49 BLAST hits in the query sequence. In the list shown in figure 7.2, there is a list of hits starting with the best (most similar). To the right of the screen is the E-value. This is the expected number of chance alignments; the lower the E value, the more significant the score. First in the list is the sequence finding itself, which obviously has the best score. To the left is the accession number. This refers to a unique code that identifies a sequence in a database. It is important to know that there is no set cut-off that determines whether a match is significant or similar enough. This must be determined according to the goals of the project. The sequences provided in the figure 7.2 show a significant alignment with Pseudomonas japonica. It shows a high score (bits) and a low E-value. Note that the lower the E value, the greater the likelihood that the sequence is a good match. BLAST output can be delivered in a variety of formats. These formats include HTML, plain text and XML formatting. For the NCBIs web-page, the default format for output is HTML. When performing a BLAST on NCBI (National Centre for Biotechnology Information), the results are displayed in a graphical format showing the following: The hits found A tabular form showing sequence identifiers for the hits with scoring related data Alignments for the sequence of interest and the hits received with corresponding BLAST scores for these. The easiest to read and most informative of these is probably the table. The main idea of BLAST is that there are often high-scoring segment pairs (HSP) in a statistically significant alignment. BLAST searches for these high scoring sequence alignments between the query sequence and the sequences in the database. The speed and relatively good accuracy of BLAST are among the key technical innovations of the BLAST programs. Sequence of events to be followed when performing a BLAST search.: Go to PUBMED (http://www.ncbi.nlm.nih.gov/pubmed/) Scroll down to reach a heading called POPULAR Under POPULAR click on BLAST Click on nucleotide blast Under the heading, enter accession number(s), gi(s), or FASTA sequence(s), type or paste the sequence that you want matched. Click BLAST Wait for the results. Analyse the nucleotide sequence as it appears. Calculation of Melting Temperature The melting temperature or Tm is a measure of stability of the duplex formed by the primer and the complementary target DNA sequence and is an important consideration in primer design. Tm corresponds to the midpoint in transition of DNA from the double stranded to its single stranded form. A higher Tm permits an increased annealing temperature that makes sure that the annealing between the target DNA and the primer is specific. The Tm is dependent on the length of the oligonucleotides and the G+C content of the primer. The formula for calculation of Tm is given in table 7.1. Table 7.1: Formula for calculation of the melting temperature. Length of Primer Tm ( °C) Less than 20 nucleotides long 2(effective length*) 20 to 35 nucleotides long 22 + 1.46(effective length) *Effective length = 2(number of G+C) + number of (A + T) Primers are usually designed to avoid matching repetitive DNA sequences. This includes repeats of a single nucleotide.. The two primers in a PCR reaction are not homologous to each other and their complementarity can lead to formation of spurious amplification artifacts called primer dimers. The 3 end of a primer is most critical for initiating polymerization. The rules for selecting primers in addition to those already mentioned are as follows: The C and G nucleotides should be distributed uniformly throughout the primer and comprise approximately 40% of the bases. More than three G or C nucleotides at the 3-end of the primer should be avoided, as nonspecific priming may occur. The primer should be neither self-complementary nor complementary to any other primer in the reaction mixture, in order to avoid formation of primer-dimer or hairpin-like structure. All possible sites of complementarity between the primer and the template DNA should be noted. The melting temperature of flanking primers should not differ by more than 5 °C. Therefore, the G+C content and length must be chosen accordingly (a higher G+C content means a higher melting temperature). The PCR annealing temperature (TA) should be approximately 5 °C lower than the primer melting temperature. G+C content in each primer should not be more than 60% to avoid formation of internal secondary structures and long stretches of any one base. Primer extension will occur during the annealing step. Primers are always present in an excess concentration in conventional (symmetric) PCR amplification and, typically, are within the range of 0.1M to 1M. It is generally advisable to use purified oligomers of the highest chemical integrity. Primer Dimers A Primer Dimer (PD) consists of primer molecules that have attached or hybridized to each other because of strings of complementary bases in the primers. As a result, the DNA polymerase amplifies the PD, leading to competition for PCR reagents, thus potentially inhibiting amplification of the DNA sequence targeted for PCR amplification. In the first step of primer dimer formation, two primers anneal at their respective 3 ends. The DNA polymerase will bind and extend the primers. In the third step, a single strand of the product of step II is used as a template to which fresh primers anneal leading to synthesis of more PD product. Primer dimers may be visible after gel electrophoresis of the PCR product. In ethidium bromide stained gels, they are typically seen as 30-50 base-pair (bp) bands or smears of moderate to high intensity. They can be easily distinguished from the band of the target sequence, which is typically longer than 50 bp. One approach to prevent PD formation consists of physical-chemical optimization of the PCR system, i.e., changing the concentration of primers, MgCl2, nucleotides, ionic strength and temperature of the reaction. Reducing PD formation may also result in reduced PCR efficiency. To overcome this limitation, other methods aim to reduce the formation of PDs only. These include primer design, and use of different PCR enzyme systems or reagents. Nuggets Oligonucleotide primers are short fragments of single stranded DNA (17-30 nucleotides in length) that are complementary to DNA sequences that flank the target region of interest. They dictate which region of DNA in the PCR will be amplified. Primer sequences can be obtained by reviewing previously published literature. A confirmation of the sequence can be done by using BLAST (Basic Local Alignment Search Tool). The melting temperature is the midpoint in the observed transition from a double stranded to a single stranded form. A higher annealing temperature ensures that the annealing between the target DNA and the primer is specific. A primer dimer consists of primer molecules that have attached or hybridized to each other because of strings of complementary bases in the primers. Taq polymerase amplifies the primer dimer leading to competition for the PCR products. Several methods are used to reduce primer dimer formation including changing the concentrations of primers, MgCl2, nucleotides, ionic strength and temperature of the reaction. TAQ DNA POLYMERASE The initial PCR reaction used the Klenow fragment of Escherichia coli DNA polymerase. However, this was unstable at high temperatures and it was necessary to add a fresh aliquot of enzyme after every denaturation step. The annealing and extension temperatures had to be kept low and as a result, there was formation of non specific products in abundance. The discovery of the thermostable Taq DNA polymerases ensured that the PCR did not remain a laboratory curiosity. The extension and annealing temperatures could now be kept high and the formation of non specific products was greatly reduced. Taq became famous for its use in the polymerase chain reaction and was called the Molecule of the Year by the journal Science. Why Taq? Taq is the enzyme of choice in PCR because of the following reasons: Taq works best at 75 °C80 °C, allowing the elongation step to occur at temperatures which make non-Watson-Crick base pairing a rare event. It can add upto 1,000 nucleoside triphosphates to a growing DNA strand. Taq has a half-life of 40 minutes at 95 °C and 9 minutes at 97.5 °C, and can replicate a 1000 base pair strand of DNA in less than 10 seconds at 72 °C. Because of all these properties, Taq is the enzyme of choice in the PCR. How does Taq polymerase act? The first requirement is a primer. The primer is annealed to the template strand having free hydroxyl group at its 3 end. During the extension phase, the Taq synthesizes a new DNA strand complementary to the template by adding dNTPs in a 5 to 3 direction condensing the 5 phosphate group of the dNTPs with the 3 hydroxyl group of the end of the extending DNA strand. Since Taq works best between 70 °C- 80 °C, a temperature of 72 °C is usually chosen as the optimum annealing temperature. Where does Taq come from? In Thermus aquaticus, Taq polymerase is expressed at very low levels and commercial production is not economically viable. However, the enzyme can now be produced from different versions of the engineered Taq gene so as to obtain high levels of expression in E coli. What other polymerases are available for use in PCR? Taq is not the only polymerase; other polymerases are available but Taq is the one that is generally used in a PCR. A few other polymerases with their uses are as follows: PFU DNA polymerase -Found in Pyrococcus furiosus, it functions in vivo to replicate the organisms DNA. The main difference between Pfu and alternative enzymes is the Pfus superior thermostability and proofreading properties compared to other thermostable polymerases. Unlike Taq DNA polymerase, Pfu DNA polymerase possesses 3 to 5 exonuclease proofreading activity, meaning that it works its way along the DNA from the 3 end to the 5 end and corrects nucleotide-misincorporation errors. This means that Pfu DNA polymerase-generated PCR fragments will have fewer errors than Taq-generated PCR inserts. As a result, Pfu is more commonly used for molecular cloning of PCR fragments than the historically popular Taq. However, Pfu is slower and typically requires 1-2 minutes to amplify 1kb of DNA at 72 ° C. Pfu can also be used in conjunction with Taq polymerase to obtain the fidelity of Pfu with the speed of Taq polymerase activity. TFL DNA polymerase Obtained from Thermus flavus, it is useful for the amplification of large segments of DNA. WHAT IS FIDELITY? All DNA polymerases have an intrinsic error rate that is highly dependant on the buffer composition, pH of the buffer, dNTP concentration and the sequence of the template itself. The types of errors that are introduced are frameshift mutations, single base pair substitutions, and spontaneous rearrangements. Therefore, the PCR reaction generates a product that is very similar, but in many cases, not identical to the original sequence. The quantity of dissimilar product obtained is obviously related to the cycle in which the mismatch took place. Under normal circumstances, this does not make any difference; however, these errors may become significant during sequencing when the role of fidelity comes into play. Fidelity is the ability of the polymerases to avoid the incorporation of wrong nucleotides during the reaction. Under normal circumstances, it really does not make a difference if a wrong nucleotide is incorporated because the size of the PCR product remains the same and that is what we have to look for. However, there are some polymerases like Pfu which have a high fidelity. In addition to reading from the 5 to the 3 direction, they can also read from the 3 to the 5 direction and correct the wrong nucleotides wh