Reading Schedule

Week 1 Tuesday 01/15 Introduction/Syllabus/ â€Å"Where I’m From† poem Thursday 01/17 Read â€Å"Brainology† by Carol Dweck Week 2 Tuesday 01/22 Read â€Å"Ain’t I a Woman† and â€Å"The Men We Carry In Our Minds† Thursday 01/24 Active Reading and Analysis Standards (posted on Blackboard under writing and reading tools) Week 3 Tuesday 01/29 Read â€Å"Narration† in Patterns; Read I Love Yous Are for White People Ch. 1-3 Thursday 01/31 Read I Love Yous Are for White People Ch. 4-5 Week 4 Tuesday 02/5 Read I Love Yous Are for White People Ch. 6-7 Thursday 02/7 Read I Love Yous Are for White People Ch. 8Week 5 Tuesday 02/12 Read I Love Yous Are for White People Ch. 9-11 Thursday 02/14 Read I Love Yous Are for White People Ch. 12 Week 6 Tuesday 02/19 Read I Love Yous Are for White People Ch. 13-14; Read I Love Yous Are for White People Epilogue, â€Å"About the book† and â€Å"Read on† Thursday 02/21 Read â€Å"Descriptionâ €  in Patterns page 143-148; Read â€Å"Exemplification† in Patterns page 199-201; Read â€Å"Process† in Patterns page 199-201 Week 7 Tuesday 02/26 Read â€Å"Cause and Effect† † in Patterns page 321-326; Read The Kite Runner pages 1-47 Thursday 02/28 Read The Kite Runner pages 48-58 Week 8Tuesday 03/05 Read â€Å"Comparison and Contrast† in Patterns page 383-384; Read The Kite Runner pages 59-100 Thursday 03/07 The Kite Runner pages 101-124 Week 9 Tuesday 03/12 Read Classification and Division in Patterns pages 447-448 The Kite Runner pages 125-189 Thursday 03/14 The Kite Runner pages 190-223 Week 10 Tuesday 03/19 Read â€Å"Definition† in Patterns page 505-506; The Kite Runner pages 224-272 Thursday 03/21 The Kite Runner pages 273-292 Week 11 SPRING BREAK Tuesday 03/26 No Class Thursday 03/28 No Class Week 12 Tuesday 04/02 The Kite Runner pages 293-371 Thursday 04/04 Read â€Å"Argumentation† in Patterns page 547-548 Week 13Tuesd ay 04/09 Read â€Å"Combining The Patterns† in Patterns page 705-706 Thursday 04/11 Read Scholarly Source Week 14 Tuesday 04/16 Read â€Å"Using Research in Your Writing† page 757-766 Thursday 04/18 Read â€Å"Using Research in Your Writing† page 766-782 Week 15 Tuesday 04/23 Read Scholarly Source Thursday 04/25 Read Scholarly Source Week 16 Tuesday 04/30 Read Scholarly Source Thursday 05/02 Read Scholarly Source Week 17 Tuesday 05/07 Read Scholarly Source Thursday05/09 Read Scholarly Source Week 18 Tuesday 05/14 Read Scholarly Source Thursday 05/16 Read Scholarly Source Week 19 Finals Week Tuesday 05/21 Final Exam

An Alternative Approach – the Unfolding Model of Voluntary Employee Turnover

An alternative approach: The unfolding model of voluntary employee turnover Lee, Thomas W; Mitchell, Terence R Academy of Management. The Academy of Management Review; Jan 1994; 19, 1; ABI/INFORM Global pg. 51 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

Performance Evaluations Essay Example | Topics and Well Written Essays - 1250 words

Performance Evaluations - Essay Example Plant engineer performance can be evaluated on criteria such as central services’ design, provision of technical support to maintain plant equipment and facilities, energy saving and production cost of energy (Amrine, Ritchey, Moodie, and Kmec, 2009). Similarly, specific criteria should be used to evaluate the performance of the employees according to their position. Secondly, the evaluation of an individual’s behavior is very essential for the provision of good outcomes, employees must have good behavior with each other; because collective decision making, work sharing, putting ideas for improvement and taking extra responsibility; helps in making organization productive. Therefore, behaviors of one employee with work and with peers should be evaluated. Behavioral evaluation is necessary for plant engineer because he has to work with others and if employees are not happy with him; they will not help him in making satisfactory outcomes. Third, the performance evaluation should be based on individual traits. This is the weakest criteria, but still it is widely used by organizations. Traits such as looking busy, having a good attitude, coming on work on time or before time and having experience are not significantly connected with optimistic results of tasks or may be connected (Robbins, Judge and Sanghi, 2009). Fourth, professional development is also an important criterion for performance evaluation. In such criteria, it is considered that either employee is continuing with his/her education, struggling for excellence, searching for opportunities in order to learn and grow and other such factors. By using different criteria, company and managers identify the strengths and weaknesses of employees. Performance evaluation criterion is an effective tool for the betterment of the organization. From analyzing the outcomes of the tasks, organization can assess

Introduction for lab report Iron in Soil and Coal Essay - 1

Introduction for lab report Iron in Soil and Coal - Essay Example Coal falls in the group of organic contaminants of soil. The iron concentration on in coal is limited compared to the iron in soil. As a result, the carbonaceous soils from coal mineral wastes provide an effective control for acidity in leachate. Iron appears in different forms in the soil. Its concentration in the soil can affect the drinking water due to the environmental concentrations in some parts of the world. This calls for the need for measuring the iron concentration in soil and coal. Various analytical methods are available for arsenic measurement in various environmental samples. Some of them include neuron activation, hydride generation atomic absorption and the inductively coupled plasma atomic emission spectrometry. Most of these approaches require expensive equipment to measure the iron concentration in soil. However, the Spectrophotometer is effective equipment in measuring the iron in coal and soil. The sample is placed in a hydrochloric acid solution followed by a measurement of Spectrophotometer using silver diethyldithiocarbamate which is the reagent that forms colour. From the colour outcome, the concentration of iron in the coal or soil is determined (Paolo Desogus

Using the key studies from the course, suggest what answers Essay

Using the key studies from the course, suggest what answers psychologists can give to the question Who am I - Essay Example logy, even though had reached great heights as far as the theories are concerned, has failed to create a revolution in the society and has proved quite helpless to transform the human nature. (Gross Richard , 2003,Pg.3). But even then, psychologists have done their best to understand the complex creation called the man and tried their best to answer the question, â€Å"Who am I?†. stagnant or a physical thing. It is a volatile and ever-changing aspect of human being and so the question can be answered in different ways. Following are some of the answers that we can come up with. I am the one who try to study and perceive people, events, relationships, the society and the system that I live in. I try to increase my understanding of everything around me using all the sensory abilities that I have so that I can have a control over my life. That is my motivation of the life, to control it and feel powerful and happy about it(Gross Richard , 2003, Pg.13). I am a product of my culture. The culture that I am born into influences me in every way. My thoughts, my behavior pattern, my beliefs, my religion, the food that I eat and the clothes that I wear are nothing but the influences of the I am the most superior of all the species. No other species can beat me when it comes to the ability of communication. I can interpret symbols and make references out of it. I can understand and communicate the things that are not in the space and time. I can mix different parts of the language and form a sentence that makes a sensible meaning. And my most powerful ability is creativity which makes me the most interesting and intelligent species on the earth ( Gross Richard , 2003, Pg.81). Even

Emerging Adulthood Essay Example | Topics and Well Written Essays - 1000 words

Emerging Adulthood - Essay Example At this time, young people are mostly pursuing education, completing their academic studies and/or determining their adulthood destiny. They engage in a moment of deciding who they are and what they want out of school, work and love (Munsey, 2006). Their minds, in a confused progressive continuum, are unstable. For example, they are mostly torn between pursuing further education or settling and living with friends, romantic partner and working (Munsey, 2006). Separated from parent care and academic routines, young adults try to define their social niche in a particular society. The in-between feeling is marked by the stance where young adults claim that they are taking responsibility for themselves yet, from within, they do not feel completely like adults (Arnett, 2010; Munsey, 2006). While their minds are filled with constant optimism, expected adulthood outcomes are diverse. There is quite a wide array of differences between this period and adolescence and adulthood. Adolescents, to start with, are continuously under the care of parents and school mentors. As so, they virtually get everything that they required at their disposal. At the ages above 12 and 19, children are thus unable to differentiate between the achievements and motives of their parents and other adults from theirs (adolescents’). They thus engage in utopian optimism thinking that everything is possible. On the contrary, emerging adults have a taste of adulthood and thus engage in experimentation of adult experiences. In academics, despite following traits of say a predefined role model, young adults undergo differentiation process where their choice of say a course of study is governed by their abilities manifestation. They specifically tend to negate from their parents’ choices upon realization of who they are and what they want to be later in life. Needless to say, young adults exhibit cognitive development by realizing cultural trends, societal

Making a theory Essay Example | Topics and Well Written Essays - 2500 words

Making a theory - Essay Example More over it has got a five button mouse, which will assist the user working in a natural way.2 Using a pen tablet with its matching point will help the user to get the design displayed on the screen exactly what he draws on the tablet. The pressure sensitivity is yet another feature of the product, it lets the user to have a control over the software tools such as brush size, opacity and other things can be controlled dynamically.3 The tablet has a Ergononic design with sloping control palm , in addition to multiple cod positions for generator work and space flexibility. Above all it has enhanced resolution and available in various sizes. The Grip Pen has 11024 levels of tip and eraser pressure sensitivity for control, battery free technology, multi-position pen stand three nib styles and tilt sensitivity. The five button mouse has a smooth and accurate tracking without ball or optic functioning with battery free technology.. Previously were using only a scanner or a Paint Brush soft ware to draw something, and then came Auto Cad, which too helped in drawing diagrams of machines and tools with help of pre fixed shapes such as straight lines, circles, rectangle, etc. But INCUOS.3 has gone forward more steps further and the easy way to develop a graphic design is very clearly seen in this method. The flexibility which this product gives has all the reason behind my attraction towards this product. When you find your imagination take its shape with colors and you get the chance immediately to view your dream spot or painting or thought with a realistic touch, the happiness you get is immeasurable. The INCUOS.3 Graphic Pen Tablet , I would say with least hesitation that, is it a yet another invention, a miniature of a dream factory. Usually a cinema world is called a dream factory, where those things we imagine are given life for quiet some time and there we get a partial but better satisfaction that

International Business Cultures Essay Example | Topics and Well Written Essays - 1500 words - 3

International Business Cultures - Essay Example Globalized business environment causes the flow of human resources from one nation to the other. Managers and employees are required to communicate with people from different backgrounds in a globalized business environment. It is essential for international business concerns while operating in a foreign nation to be able to adapt themselves with the cultural beliefs and values existing in the society of the host country (Bennett, Aston and Colquhoun, 2000). In this reflective report the cultural difference existing between the nations of the U.K. and China have been studied. Both the U.K. and Chinese organizations are observed to have distinctive cultures. The cultural dissonance existing between these nations have been analysed in this report. From my perspective, it is important to study the cultural difference existing between different nations as it helps in taking measures for bridging the gap and develop business ties across international boundaries. The difference in the cultural perspectives is seen to arise from the difference in governance, value system, social thinking, attitude and behaviour. The cultural dissonance acts as a barrier for effective communication. This paper speaks about the cultural differences existing between the U.K. and China as understood by me. The analysis and research work that was conducted by me reveal that employees in the U.K. interact in a casual manner while transacting business or communicating with each other. Casual relationships are seen to be a part of their organizational culture. Business entities are seen to communicate with each other directly in a less formal manner. The U.K. based organizations believe that when casual relationships enhance direct attachments. The direct associations between different organizations are important to transact more efficiently. In the context of China

Chi-Globalization Term Paper Example | Topics and Well Written Essays - 2000 words

Chi-Globalization - Term Paper Example Chi globalization encompasses the creation of a society with various specific features such as pragmatism, inter-culturalism and multiculturalism. This concept is basically a demonstration of a process that involves china’s engagement in the diverse aspects of civilization and development of globalization. Concerns revolve around the creation of globally enlightened world with the aim of facilitating and enhancing the lives of people from the point of view of a Eurocentric model. Chi globalization can be viewed as being both intercultural and bicultural. From the bicultural viewpoint it basically has its foundation on the emergence of the Chinese model that followed from china’s fusion with western and eastern cultures (Killion, 2006, p.45). The fusion of the different cultures has its origin from the opium war which took place in the 1850’s. In this case chi globalization occupies quite an integral part in the history as well as the current state of china in rel ation civilization and development (Alon, Ilan and John 2008, p.37). A study of what drove forth towards the existence of Chi globalization indicates that Anglobalization is a major factor. On the other hand Chi globalization being understood as being something that is intercultural two processes are involved. The first process presents that it is an opportunity created for china to open and embrace other cultures form other people. The second process demonstrates that chi globalization is involves the identification and incorporation of other cultures into the Chinese culture for instance the African culture, Latin American culture among others. An in-depth analysis of chi globalization presents some unique factors that have played quite a major role in its development. The globalization of America forms an important in this discussion. This is due to the fact it is the fundamental basis in which chi globalization grew out of. In connection to this the United States has acted as a model for china from the economic, cultural and social perspectives. Most aspects of civilization and development in china have simply been a reflection of what is happening in the United States (Veeck, Pannell, Smith and Huang 2007, p.60) For years America has been a major consumer of china made goods providing a reliable market even when the state is hit by a financial crisis such as the Wall Street crisis. On the same not America has had interest and created ties with china through engagement in foreign direct investment. Most of the ideas and strategies that have been used to drive china’s development have sourced from the United States thus making America a major source inspiration for the state of china. Up to this point on the higher side the American dream is in a way the dream for china. Therefore china has some fundamental values similar to those understood to facilitate the development of globalization in the United States. Such values include the free flow of both ideas and information and free flow of capital and goods. Despite Chi globalization borrowing a lot from Ameriglobalization and Anglobalization there are some unique values that make it differ in a way. This is due to the fact that it highly relates more to the culture in china. Increased identification with the world of Ameriglobalization and Anglobalization makes the way of life for the Chinese people a global model aimed at fostering development that fits the

Eating Disorder Research Paper Essay Example for Free

Eating Disorder Research Paper Essay Media and society are often looked at as a source of daily entertainment, gossip and news. Every day, people are constantly exposed to thousands of images of glamour, beauty, celebrities, and much more. The media is so compelling that it has the power to change what people believe in. The images that are shown repeatedly make a way into teenagers mind and they want to be a part of what the media shows. Teens feel the need to change their body to look a certain way and be like someone else. But a fact unknown to teenagers is that even celebrities’ body are not perfect. The most common eating disorders are anorexia nervosa and bulimia nervosa. People with anorexia have a huge fear of gaining weight and a change in their body shape and size (â€Å"Eating Disorders†). Anorexia has been characterized as a â€Å"rich white girl† disorder because most anorectics are white and about three-quarters of them come from households at the middle income level or above (Davidson and Fundukian). Bulimia on the other hand is when a person eats large amount of food over a short period of time then later performs activities to try to burn the calories off. Binging is the most common symptom of bulimia and it is often done when trying to get rid of the food eaten. Bulimia is thought to affect around 1% to 5% of teenage American girls and up to 3% will be bulimic at some point in their life (Arnold and Walsh 30). Studies show that â€Å"media exposure has a direct impact on disorder symptoms and indirect effects through gender role endorsement, ideal-body stereotype internalization and body satisfaction. † The covers of magazines display pictures of both men and women whose images are offered as near perfection in society. â€Å"Research has shown that even brief exposure to ads showing highly attractive models results in decreased satisfaction with ones own appearance† (McMurray). Teenagers should know that celebrities are not magically beautiful and thin, they are made to look that way. â€Å"Today’s culture is unique in that the media is a far more powerful presence than ever before† (Derenne and Bersin). The media has been named as a causative factor for body dissatisfaction, which promotes unrealistic standards of female beauty and show images that create and reinforce cultural definitions of attractiveness. (Qtd. in Wexler). The media opens the door of eating disorders to teenagers and brainwashes them into thinking that being thin is important and necessary. The media needs to be very careful in the messages that they give to teenagers regarding body image. Dr. Bond says how â€Å"the media should be more responsible in not publishing pictures of very thin models and celebrities because young people wish to emulate them. Eating disorders are not going away, if anything they are becoming more common (Thinspiration? ). Advertisements everywhere continually expose the notion that losing weight will make people happier. Advertisements that show thin celebrities reach out to individuals telling them what they can be or become if they were thin. By looking at these advertisements, women start to feel insecure about the way they look. The NEDA reports that â€Å"women’s magazines contained 10. 5 times more advertisements and articles promoting diet and weight loss then were found in men’s magazines. It also reports that a study of 4,294 network television commercials revealed that one out of every 3. 8 commercials conveyed some sort of attractiveness message of what is or is not attractive† (Qtd. In Wexler). Many women frequently compare their bodies to those around them and the body images on advertisements lowers their self-esteem. The advertisements of celebrities affects the stereotypical idea of an ideal body which leads to eating disorders (Stice et al 5). Online, there are websites that promote anorexia. Teens with anorexia can then put up pictures of their skinny bodies for other anorectics to see and feel encouraged by. They feature pictures of celebrities such Keira Knightley and Victoria Beckham that promote 400-500 calories a day diet. In a year alone more than 500,000 people visited the sites and a 2011 EU survey found more than one in five six-to 11-year olds had been exposed to one or more sites with these â€Å"harmful content† (Thinspiration? . Teens who are anorexic feel that having an eating disorder is not a bad thing. They look upon each other for support, telling each other secrets of losing weight. The quote â€Å"Nothing tastes as good as skinny feels† by Kate Moss is popular among these pro-anorexia websites (Wardrop). TV shows also send the message to be thin to whoever watches them. Disney Channel, which attracts millions of viewers, especially the young, made fun of eating disorder and actually promoted the idea of being thin. In the show Shake It Up, someone stated â€Å"I could just eat you guys up, you know, if I ate† (â€Å"Party It Up†). In another Disney show, So Random, a conversation goes on where one character tells another â€Å"Angus only eats one full meal a day† to which Angus replies â€Å"My agent’s always on me about looking my best (Colbie Caillat). Disney thinks about eating disorders as a joke which is not dangerous. For many kids, the people on Disney are their role models, and if kids see their role models not eating, they are going to think that it is okay to not eat. Also if Disney encourages the idea of not eating that kids will do the same thing. Demi Lovato who battled an eating disorder attacked Disney about these risky messages that they send to kids. Experts say that Lovato opened the Pandora’s Box about the dangerous effects television shows can have on the negative body image of young women (â€Å"Disney Pop Star†). Even in other TV shows, the overweight characters are most likely portrayed as lazy and the one with no friends, while thin characters are successful and popular. This also sends a message that in order to be successful in life a person has to be thin. Teenagers feel pressured into looking the way society wants them to look like. Everywhere they go, they see posters of celebrities enhanced to look â€Å"perfect. Society thinks that if someone does not look a certain way then it is not acceptable and that they should change how their body looks. From a young age, women are given the message that in order to be happy, they must be thin. Thousands of teenage girl starve themselves to attain what the fashion industry considers to be the â€Å"ideal† figure (Thompson). Society has become obsessive and prejudiced when it comes to body image. Society and media work together to get that one message across to teens today; to be thin. New diets come out every month and media spends money trying to advertise them and get celebrity endorsements. In stores, the front pages of magazines show that one celebrity that everyone looks up too. How they talk about that one diet that â€Å"changed their life† and made them â€Å"happy† again. Teens think that if these celebrities can be skinny, then why can’t they? Teens spend their times looking at websites and magazines that tell them how to be skinny. By constantly portraying â€Å"perfect† bodies in the media, it promotes unhealthy eating that can sometimes lead to death (â€Å"Disney Pop Star†). Even today, dolls like Barbie send that message to young girl to be thin. The Barbie doll is a stereotype of a woman with no flaws and a perfect body who gets to be whatever she wants. Girls who play with Barbie feel the need to look and act like her. The traditional Barbie is known for her 40-18-32 measurements (Young) which would be unproportional on human bodies (Grey). If Barbie were real, she would be 59 tall and weigh 110 pounds, about 35 pounds below the minimum healthy weight for a woman of that size (McMurray). Barbie helps to perpetuate an ideal of materialism, beauty, and being thin is happiness and since a young age, the desire to be thin is recognized by girls everywhere. But eating disorders doesn’t just affect women, it affects men also. In a study by Harvard researchers, 25% of 3,000 adults had anorexia or bulimia and 40% of binge eaters were men (Boodman). Just like women, men also feel pressured into looking a certain way. In school, boys are told to be healthy if they want to keep playing a sport. But that habit can become something more dangerous. â€Å"Studies show that gay males particularly place a higher calculation on thinness than heterosexual males, with a level of concern for thinness almost equal to that of the typical heterosexual female† (Anderson, Cohn, and Holbrook 41). Because of this many men might be afraid about coming out to the world about their eating disorder. Some people think of an eating disorder as more of a woman thing and â€Å"psychological tests for eating disorders are biased towards diagnosing women† (Anderson, Cohn, and Holbrook 41). Eating disorders are also common in the entertainment business. Celebrities and models are also under pressure to look their best. The average model weighs 23% less than the average woman and fit the category of being anorexic (Thompson). Models go through plastic surgery and photos are air-brushed before going to print. The body type and images are unobtainable to the average individual and the constant force of these images on society makes teens believe that they should be. Many celebrities and models who feel that an eating disorder is something more dangerous than what everyone else seems have come out and talked about that issues. Even celebrities who once had an eating disorder spend time educating others and telling them that it is okay to get help. In 1992 after the news about Princess Diana being bulimic was released, there was a significant increase in the number of bulimia diagnoses. This effect then came known as the â€Å"Diana Effect† (Celebrities Who Battled Eating Disorders). Just like how Lucy Grealy states in her memoir Autobiography of a Face, Beauty, as defined by society at large, seemed to be only about who was best at looking like everyone else (187) it looks like that concept has not changed since that time. In today’s society everything is about being thin and trying to look like a model or a celebrity. Teenagers try to do everything to make themselves how society wants it but in the end they just destroy themselves. Society and media think of an eating disorder as a joke but it is a disease; a disease that has the power to take the lives of both women and men. For anybody out there who thinks that an eating disorder is not a big deal then they are wrong. People, especially the media, should know that the message they send out to teens is wrong; everything is not just about being thin. Simply by the media bringing out the concept that being beautiful and thin is necessary for a successful life is wrong. Having to look like a model to be accepted in society is wrong. All these messages have a huge negative effect on teenagers and they think down of themselves just because they do not think they are â€Å"right† for society. The fake advertisements that are shown is just another step for teens to developing a dangerous and deadly addiction that is called an eating disorder. â€Å"I think we look at society and we look at every ad that out there and everything that tells us how we’re supposed to look, and how we’re supposed to live, and how we’re supposed to be instead of saying ‘Is that how really I feel? ’, ‘Is that really what I want to do? ’, and ‘Is that really how I want to live? ’† (Ellen DeGeneres).

Mechanisms Of Conservative And Replicative Transposition Biology Essay

Mechanisms Of Conservative And Replicative Transposition Biology Essay Bacteriophage Mu is a temperate phage which adopts transposition pathway in its life cycle. Mu has the capability to integrate into numerous sites in host Escherichia coli genome and cause mutations due to its insertional activation. Mu transposes via two major pathways; conservative and replicative transposition though the molecular switch between the two mechanisms remain unknown. This review will focus on the comparisons between replicative and conservative transposition. The first part will discuss the similarities between the two mechanisms; donor DNA cleavage step and strand transfer step which involves nucleophilic attacks, generating single-strand nicks in Mu DNA and joining it to target DNA via one-step transesterification mechanism. The latter part will concentrate on the different characteristics in each transposition mechanism; in replicative transposition, the end product is duplication of transposon copy in both target and host DNA while in conservative transposition, a simple insertion of transposon is produced in the target DNA. 1. Characteristics of bacteriophage Mu Phage, derived from the Greek word phagein, literally means to eat. Bacteriophage Mu was named as such(find out who did) due its nature of infecting and inducing high levels of mutation in host bacteria Escherichia coli., hence the name Mu for mutator. The dual nature of Mu transposon and virus has made it as the archetypal model of studying phage genetics. Bacteriophage Mu is a temperate phage of E. coli which employs the transposition mechanism in its life cycle. Transposition can either be conservative (excising the transposon and inserting it into bacterial chromosome) or replicative (transposon copies are produced in both transposon and bacterial chromosome). Both mechanisms will be discussed extensively later in this article. Unlike the phage ÃŽÂ », insertion of Mu genome into the target site proceeds in a randomly manner which makes it an excellent mutator. Fig. 1: The life cycle of bacteriophage Mu(5). The life cycle of phage Mu is shown schematically in Fig. 1 above. Bacteriophage Mu infect susceptible host cell by adsorption and then, injects its linear viral genome. Once inside the host cell, the linear genome does not circularized(4,5,19), unlike in phage ÃŽÂ ». In either case of lytic or lysogenic phase, Mu integrates its DNA into the host genome via conservative transposition(16,19). This is observed differently in phage ÃŽÂ » where the infecting phage DNA will be integrated into host genome only during lysogenization(19). An enzyme called transposase, encoded by MuA gene in the phage genome, is absolutely crucial to carry out this conservative transposition step. Phage DNA is inserted at multiple sites in a bacterial genome which lead to the assumption that the insertion occur by a random manner(8). However, there are several factors that influence target site selection such as MuA protein efficiency and transposition immunity(15). After integration, Mu usually adopts a quiescent prophage lifestyle(lysogenic phase). The preference between lysogenic and lytic phase in Mu life cycle is dependent on its stability in the lysogen and lysogenic repressors. However, lysogens of Mu phage sometimes enter the lytic phase though this is a rare event. When induced, usually by using temperature-sensitive repressor mutants of phage Mu and subject it at 42ËÅ ¡C, the lysogen will enter lytic cycle. When the lysogenic repressor is inactivated, Mu transposes via replicative transposition, producing copies of phage genome which will be packaged into new virions. The virions then lyse the host cell and infect new hosts. Bacteriophage Mu virions comprised of icosahedral head(diameter 54nm), a baseplate, a contractile tail and six short tail fibres(5). Fig. 2: Simplified cartoon illustrating packaging of Mu genome. Typical length of phage Mu DNA is approximately 37kb long. Additional 2 kb of host DNA is incorporated during DNA packaging which is shown as flanking each end of the integrated Mu genome, with most of it at the right end. Unique sequences of host DNA and at the right end of the packaged DNA is dependent on initiation site of packaging in the host DNA(24). Fig. 3: Physical and genetic map of bacteriophage Mu. Solid black lines represent Mu DNA while the boxes at the two ends indicate flanking host DNA sequences. Mu genes (indicated in block letters) and their corresponding translational products are as indicated(19). A typical size of wild-type phage Mu DNA is about 37.5 kb, however each phage capsid can accommodate up to 39 kb long. Phage genome has a pac site which serves as the starting point in packaging of the phage DNA, located within attL(5). The initiation cleavage by phage enzyme terminase occurs upstream of the phage pac site, which includes host sequence of about 50-150bp flanking the left end. Second cleavage initiated when a complete filling of capsid is achieved, which includes 0.5 kb to 2 kb of host sequence flanking the right end(1). Genetic and physical map of phage Mu is illustrated in Fig. 3. Bacteriophage Mu utilizes headful mechanism strategy, which confer variable lengths of host DNA flanking the left ends of Mu DNA depending on the initiation site of genome packaging(Fig. 2). 2. Transposition mechanism (E) (D) (C) (B) (A) Fig. 4: Modes of bacteriophage Mu transposition. (A), (B) and (C) are the common steps in both conservative and replicative transposition of phage Mu. In conservative and replicative transposition, phage Mu will follow-up step (D) and (E) respectively. Curved arrows indicate nucleophile attack, transferring the 3-OH ends to the staggered 5-phosphate ends of target DNA. Dentate lines (XXXX) indicate target DNA sequences which are duplicated during transposition (16). Numerous in vitro studies have been conducted to study the mechanism of transposition, and usually mini-Mu elements are used. A minimal Mu element consists of a selectable gene, a plasmid replication origin and essential Mu ends(2). The mechanism of transposition is discussed in respect to an in vitro system from this point onwards unless stated otherwise. Following discussion on transposition mechanism are based on Shapiro model(22) as it has been widely accepted as the golden model in this field. The current known modes of transposition is divided into two: non-replicative (conservative) and replicative transposition. Both strategies utilize the same mechanism up to point (Fig. 4C) where each strategy employs different mechanism, producing different end products. A simple insertion of transposon is generated in target DNA by conservative transposition (Fig. 4D) while two copies of transposon formed in both donor and target DNA by replicative transposition (Fig. 4E). Point A to C are considered as the similar features in both conservative and replicative transposition while point D and E is the distinction between the two modes of transposition. Therefore, mechanisms involved in point A,B and C are discussed in context of both replicative and conservative transposition, which comprises of DNA cleavage step and strand transfer step. Sequential stages of both cleavage and strand transfer steps are illustrated in Fig. 4. 2.1 Donor DNA cleavage step Two critical chemical steps in both transposition pathways are donor DNA cleavage step and DNA strand transfer step(5,8). The donor DNA cleavage step is initiated when water molecules within an active site act as nucleophiles, and attack phosphodiester bond in DNA backbone at each of the transposon end(4,5). The cleavage step involves a direct hydrolysis of phosphodiester bond by water, and not by covalent enzyme-DNA intermediate(17). The phosphodiester bond is cleaved at the flanking host-transposon DNA boundary. 3-hydroxyl (OH) ends of the Mu DNA are exposed at the end of the cleavage step. Strand transfer results in fusion of target and donor DNA, which forms an intermediate molecule (8). The process (simplified in Fig. 4C) follows the Shapiro model(22). Bacteriophage-encoded proteins, MuA protein (transposase) and MuB protein (ATPase) are required for transposition. Other requirements to ensure efficiency of transposition are accessory proteins such as host-encoded DNA bending proteins called hydroxyurea (HU) and integration host factor (IHF)(8). The inverted repeats at the end of donor DNA, and target sequence on bacterial chromosome are also important in transposition mechanism. The assembly of higher order protein-DNA complexes called transposome has been identified by in vitro studies(6). A three-site synaptic complex called the LER complex comprising right and left ends of Mu and transpositional enhancer, was formed in the beginning of transposition in vitro(23). MuA protein binds to MuA binding site at the ends of Mu DNA as monomer, and subsequently function as tetramer of MuA (transposase). Host IHF and HU protein were found to aid in formation and stabilisation of LER complex. The LER complex is relatively unstable and so, is rapidly converted into stable synaptic complex (SSC), also known as type 0 complex(17). This is the critical checkpoint before any chemical reaction is carried out as it is the rate-limiting step of cleavage reaction(6). A stable synapse between tetramer of MuA and the two ends of Mu DNA is made but no cleavage is initiated yet at this point. Nonetheless, the active site is structurally occupied to the region around the scissile phosphate while the flanking DNA are destabilized upon formation of the SSC complex(6). In addition to formation of a stable synapse, the Mu ends needs to be properly-oriented, a super coiled DNA topology, and accessory DNA sites are also important to proceed to the next step. Formation of SSC usually is short-lived in presence of Mg2+ but can be accumulated in presence of suitable divalent cations such as Ca2+,which promotes the formation of SSC(8,17). Next, SSC is converted into a type 1 transposome complex, also called as cleaved donor complex(CDC)(9). The 3 ends of Mu DNA are nicked in presence of Mg2+. Two subunits of MuA tetramer, that are associated with the sites that undergo cleavage, assemble in trans arrangement which favours the strand transfer reaction(5). The formation of CDC can then be thought as the result of donor DNA cleavage step. Type 1 transposome complex exhibits greater stability than the type 0 complex though MuA forms structural and functional core in both transposome complexes(6). In addition of stably bound tetramer of MuA proteins, there are loosely associated MuA proteins present in the CDC as well. In absence of MuB protein, MuA tetramer is unable to promote strand transfer reaction unless these extra MuA proteins are present. MuB protein is an ATP-dependent DNA-binding protein, which also acts as an allosteric activator of Mu transposase (MuA proteins)(21). Transposition can still proceed in absence o f MuB proteins, but MuA protein by itself is only 1% efficient(3). 2.2 Strand transfer step A hallmark of this step is the formation of strand transfer complex (STC), also known as type 2 transposome complex. The end product of STC is formation of a branched molecule(Shapiro intermediate) which is characterized by a covalent interaction between donor DNA and target DNA via 5bp single-stranded gaps and its ÃŽÂ ¸ structure(22). MuB protein first captures a target molecule and bring it to the vicinity of the transposome complex, forming a TC complex(6). Formation of TC complexes rapidly undergo one-step transesterification reaction, which is the rate-limiting step in the strand transfer step. Interestingly, recruiting of target molecules by MuB proteins and formation of TC complexes can occur at several time point during the reaction pathway(6). This is a particularly efficient step to maximize transposition potential as it would speed up rate of strand transfers during transposition. The free 3-OH ends produced from the cleavage step act as nucleophile and attack phosphates of target DNA at the 5 ends. 5-nucleotides long offset nicks are made in the target DNA, generating a staggered arrangement(3). At this stage, the MuA proteins(transposase) are still tightly bound to the branched molecule with single stranded gaps. This pose an obstruction for the assembly of replication fork by host replication factors. The structure of the branched molecule is simplified in (C) of Fig. 4. The forming of this intermediate molecule serves as the critical point which distinguish between conservative and replicative transposition. A widely accepted model is that the resolving of this co-integrate molecule by a special resolvase complex leads to double copies of transposon being made in both donor and target site(REFerence). This is by definition, a replicative transposition pathway. Thus, the strand transfer complex is destabilized and disassembled by a system of eight E. coli host molecular proteins (DnaB helicase, DnaC protein, DnaG primase, DNA polymerase II, single-strand binding protein, DNA gyrase, DNA polymerase I and DNA ligase) and molecular chaperon called ClpX, producing cointegrates(13). This transition from transposome complex to a replisome results in duplication of 5-bp target DNA sequences flanking both ends of Mu DNA. Alternatively, if the bacteriophage Mu is to enter the conservative pathway, the co-integrate molecule is repaired or processed without performing Mu DNA replication. The end product of STC in a conservative transposition is a simple insertion of single mini-Mu element inserted into the target DNA(8). However, the mechanism of this model is poorly understood. Fig. 5: Transposome complexes involved during DNA cleavage complex and DNA strand transfer. (A) A plasmid (gray line) bearing donor mini-Mu element (black line) DNA in the in vitro system is negatively coiled. (B) In presence of host HU protein, Mu A protein bind to the two ends of Mu DNA forming a stable synaptic complex (not shown). Assembly of MuA tetramer produces a nick at each ends of Mu DNA, creating a cleaved donor complex (CDC). (C) Nicked 3 ends of Mu DNA are joined together to target DNA in presence of MuB protein forming a strand transfer complex (STC). MuA tetramer is still tightly bound to the Mu ends in the STC. (D) In replicative transposition, a cointegrate molecule is produced when replication of target DNA initiated from the 3 Mu ends by host replication machinery (13). 3. Replicative transposition Replicative transposition was first suggested by Ljungquist and Bukhari (1977) to occur in situ after induction of lysogens, which means that the Mu prophage was not excised from host chromosome during transposition(14). The lysogens were digested with restriction enzymes which cleaves both host and Mu DNA at specific restriction sites. Two of the fragments from the restriction digests contain both host and Mu DNA, which corresponds to junctions between host and prophage DNA, suggesting that prophage DNA is replicated in situ of host chromosome(19). Several genetic and biochemical predictions made in the Shapiro model have been demonstrated in both in vivo and in vitro studies, hence this model is accepted as a plausible mechanism to explain transposition in phage Mu. Numerous techniques have been done to study the direction of replication of Mu DNA during transposition. Results obtained by annealing of Okazaki fragments to separated strands of Mu DNA shows that more than 80% of Mu molecules replication proceed from left to right end(11,19). Electron microscopical observation of mini-Mu element shows that replicating molecules in vitro replicate from both ends in equal probability'(11,19). Replication of Mu DNA is accepted to be predominantly unidirectional, that is from left towards the right end(20). Intramolecular replication pathway can result in inversion, deletion, and simple insertion while intermolecular events can produce co-integrate molecules(19). In the case of Mu transposition, formation of co-integrate molecule needs to be resolved in order to produce two replicons; one molecule contains transposon and target DNA while another molecule contains transposon and donor DNA(10). 4. Conservative transposition The main characteristic of conservative transposition is that phage DNA is not replicated prior to integration. Upon infection of a susceptible host cell (usually E. coli), Mu employs conservative, or also called non-replicative transposition to transfer its genome to the target site. As discussed earlier, conservative transposition pathway follows single strand nicks at the 3 ends of Mu DNA, of which the exposed 3-OH ends join to the staggered cut target DNA at the 5ends forming a co-integrate molecule. The co-integrate or so-called Shapiro intermediate is repaired and generates a simple insertion in the target DNA though the mechanism is still poorly understood. Shapiro model emphasized on single-stranded nicks at Mu ends, joining of Mu to a staggered double-strand break in target DNA, formation of an intermediate molecule, and shedding of heterogeneous of previous host DNA sequences after ligation in conservative pathway(22). On the other hand, Morisato and Kleckner (1984) proposed a different mechanism based on results with Tn10 transposition. Their model is double-stranded cleavages at the transposon ends generating an excised transposon, which then circularizes via ligation on one of the strands(18). It predicts shedding of host sequences from the Mu DNA ends before ligation into the new target DNA. Study of Mu transposition using plasmid substrates in vitro produced results in favour of the Shapiro model, and hence this model has been widely accepted and used in studies. Fig. 6: A model of conservative transposition which utilizes double-strand cleavages during integration. (A) Transposase bind to the inverted repeats at Mu-host boundary sites and cleaves off the transposon away. (B) Transposase made a staggered cut at target sequence of which exposed 3-OH ends of transposon attacks 5-phosphate ends of the host (not shown). The transposon then joins to the host sequence. Duplicated target sequence of 5-bp are completed by host replication machinery (7). The debate on single-strand or double-strand cleavage however does not end there. If phage Mu were to utilize the Shapiro model of transposition during integration (the well-established cointegrate mechanism), the flanking host sequences would remain bound to Mu ends. This would clearly pose a problem as subsequent target-primed replication of the linear integrant would not work, or simply break the chromosome(1). Evidently, results from in vitro experiments are against this as the transposition end products contain transposon, suggesting a complete transposition process have been accomplished. So, does the infecting Mu DNA utilize the Shapiro model where the cointegrate molecule gets processed and repaired, prior to replication at the flanking sequence? Or does it follow a cut-and-paste mechanism where both strands of Mu DNA gets cleaved off from the flanking host DNA sequence (as illustrated in Fig. 6), where no cointegrate molecule is generated, which eventually means, there is no need for resolve by replication? An in vitro experiment was done by Au et al. (2006) to observe the fate of flanking host DNA sequences upon phage Mu infection. Specific markers specific to the infecting phage Mu DNA as well as the donor host (lacZ/proB) were used. These markers were acquired from the host in which the phage had been propagated but absent in the host being infected(1). Upon infection of plasmids by bacteriophage Mu, signal for flanking sequences and Mu DNA were detected in the chromosome at the same time point (approximately at minute 8), which correspond to the integration time point of Mu. Subsequent expression of lacZ and proB were detected maximally at minute 15, significantly reduced at minute 30 and by minute 50, expression were halted(1). Maximal expression at minute 15 most likely corresponds to climax of integration of the infecting phage population. These findings strongly suggest that flanking sequences get integrated together with Mu DNA into the new target site and are subsequently, rem oved by a special mechanism(which explained the undetectable expression at minute 50). This then proves that infecting phage Mu employs an alternate cointegrate mechanism (also called as nick-join-process mechanism) in conservative transposition pathway, where the Mu DNA undergo single-strand nicks, joins to the target DNA, and repaired before replication of the 5-bp gap left by the flanking sequence(1). The mechanism of removal and repair of host flanking sequence however, remains ambiguous. Conclusion Dual nature of bacteriophage Mu, a transposable element and a virus, is certainly interesting but what is more fascinating is that it utilizes both replicative and non-replicative transposition throughout its life cycle. The former mechanism produces a transposon copy in both donor and target DNA while the latter usually generates a simple insertion of transposon in the target DNA, leaving a gap in the host DNA which most likely will get degraded. In the early stages, both replicative and conservative transposition pathway share a similar mechanism. Regardless of the transposition pathway, infecting Mu DNA during the first round of infection will integrate its DNA into the target chromosome via two critical steps; donor DNA cleavage step and strand transfer step. Mu uses a phosphoryl transfer involving nucleophilic attacks of water on phosphodiester bonds of Mu DNA, producing single-strand nicks. A second nucleophilic attack by exposed 3-ends of Mu DNA on 5-ends of target phosphodiester bonds, which then joins the Mu DNA to target DNA via one-step transesterification mechanism. A series of transposome complexes are formed throughout these processes including Mu-encoded MuA proteins(transposase) and MuB proteins(ATPase). A cointegrate is produced in both pathways but in replicative transposition, this intermediate molecule is resolved producing two replicons with transposon copy in each molecule. In conservative transposition, the cointegrate is repaired generating a simple insertion in the target DNA. Hence, it is more accurate to name conservative transposition as nick-join-process rather than the conventional cut-and-paste mechanism as the latter suggest double-strand nicks at the transposon end, which has been proven inaccurate by in vitro experiments. Both transposition pathways have been compared extensively in this review but much of functional core of the mechanisms remain to be understood. (2944 words)