The Discovery Telomerase Essay Example for Free

The Discovery Telomerase Essay The linear chromosomes of eukaryotes are more complex than the circular chromosomes of the bacteria. Due to the biochemical properties of DNA polymerases, the replication of the eukaryotic chromosomes poses a special problem: the maintenance of the length of the linear chromosomes. However, it was discovered that a unique enzyme complex appears to play a crucial in maintaining the length of eukaryotic chromosomes. This enzyme is known as the telomerase. Its regulative action on the eukaryotic cell implies that it may also be involved in the process of aging and in the development of cancer cells. In this paper, the telomerase becomes the focus of study. The discovery, properties, and functions of the telomerase inside the eukaryotic cells will be described, based on the recent scientific studies that have been conducted about them. And finally, current and potential applications that involve this enzyme, in the field of biotechnology, will be presented. The Discovery of Telomerase When the telomerase was first discovered by Carol Greider in 1984, many geneticists and molecular biologists like her have already been puzzling over the observation that the tips of chromosomes are stabilised by telomeres. Telomeres are mere regions in the DNA in which sections of them are no longer copied during the process of cell division and chromosome replication (Vermolen 2005). But the fact that a small section of a telomere is not copied should result in shorter telomeres in the daughter cells. Strangely, this does not occur and scientists can only surmise that something maintains the length of the telomere and it could be an enzyme that is yet unknown. Then, on that fateful Christmas Day in 1984, Greider found the elusive enzyme through the use of autoradiography (Skloot 2001). The telomerase is the enzyme that is responsible for maintaining the genetic material found at the tips of the chromosomes. The Properties of Telomerase The telomerase is an enzyme and this brings to mind two basic characteristics. First, any enzyme is composed of a protein. In the case of telomerase, the protein is the RNA and it can be considered as a ribozyme (Brown 2005). And second, any enzyme is a natural catalyst of all chemical reactions within the body of an organism. This means that the telomerase facilitates a vital biochemical reaction. But the exact mechanism that the telomerase executes to maintain the length of the telomere during chromosomal replication can only be determined if the properties of it are known. And the properties can be known if the specific nature of the structure of the RNA is established. The telomerase is composed of two components, the essential RNA and the TERT. The latter, which stands for telomerase reverse transcriptase, is the catalytic protein. It â€Å"contains sequence motifs homologous to those in the catalytic domain of reverse transcriptase enzymes† (Chen Greider 2004, p. 14683). This is concluded because the TERT is remains the same in all eukaryotes. The structure of the RNA component, however, is more challenging to characterise. This is because the telomerase RNA varies in terms of size and sequence. Fortunately, the overall structure of the telomerase RNA in many ciliates and vertebrates was eventually established (Chen, Blasco Greider 2000). The common process utilized was the phylogenetic analysis (Tzfati 2003). However, the characterization of telomerase RNA did not reveal similarities. There are large differences among the telomerase RNA structures of different organisms. For example, the RNA of ciliates has a conserved sequence motif found in helix I (Lai 2002), where as the RNA of yeasts seeks several helical regions as the binding sites for the telomerase’s Est1 protein (Peterson et al 2001). Thus, there was a need to ascertain a core structure. This core structure is also referred to as the secondary Blackburn (2004) and her colleagues, by using telomerase RNAs of yeasts, proposed a core structure out of the process of delineating nucleotides and base pairings. They showed that a pseudoknot structure is an essential component of the telomerase RNA because it plays an important role during the binding process. Figure 1: The TERT binding and the pseudoknot The Functions of Telomerase The most obvious function of the telomerase, as stated before, is the maintenance of the length of the linear chromosomes of eukaryotes. This is carried out through a process known as reverse transcription. But, among scientists, this general statement is insufficient, especially before the advancing knowledge in biochemistry. And now that the structure of the telomerase is established, the next question to be answered is how the telomerase actually and specifically works. There is no consensus so far, but the results of various studies can be combined to form a better picture of the function of telomerase. Here are three of the most significant ones. First, it was firmly established by several studies that there is a long-range base-pairing that occurs at the Est2 binding site (Chappell Lundblad 2004; Dandjinou et al 2004; Lin et al 2004; Zapulla Cech 2004). Second, the pseudoknot performs various functions: binding at Est2 among yeasts and other replication-related activities among vertebrates (Livengood et al 2002). And third, the TERT proteins of the telomerase locate specific domains and these domains are referred to as motif T. This motif T is vital for RNA binding (Friedman Cech 1999; Kelleher et al 2002). The specific actions of the two components of the telomerase are vital towards the determining its applications. Current and Potential Applications of Telomerase There have been several misunderstandings about the application of telomerase in the field of biotechnology. The most popular false notion about telomerase is that it is the fountain of youth. Telomerase does not make a person stay young forever. What the telomerase can do is to support the replication of the chromosome and then, after many years, allow the state of senescence. It must be remembered that the telomerase only act upon the tips of the chromosomes and not on the lifestyle of a person. This implies that if a person decides to live a dangerous or unhealthy lifestyle, neither his telomerase nor any modification on this enzyme will ever prevent his early death. The telomerase does not immortalize any organism. But this does not mean that the telomerase has no significant application. One of the most significant applications of telomerase is in the field of oncology. That is, the telomerase has been found to act abnormally during the replication of cancer cells. In normal cells, the action of telomerase ceases right after the chromosomal replication. But in cancer cells, the telomerase remains active. Scientists assume that there must be some structural difference between the telomerase of normal cells and that of cancer cells. If the structural difference is found, it might be possible for molecular biologists to seek out cancerous cells by seeking the telomerase only. Then, a person who has cancer at the early stages can be diagnosed immediately and can utilize cancer therapeutic treatments that involve the inhibition of the abnormal telomerase (Shay et al 2001). Conclusion The discovery of the telomerase is one of the most significant events in science history. It can be considered as vital as the discovery of the double helix structure of the DNA. This is because this enzyme allows the accurate and regulated replication of the linear chromosomes of eukaryotes. But, just as the discovery of the enzyme was challenging, the establishment of its properties and functions are equally difficult to carry out. Yet, molecular biologists persevere and came up with interesting possible applications of telomerase. Bibliography Blackburn, EH, Lin, J, Ly, H, Hussain, A, Abraham, M, Pearl, S, Tzfati, Y, Parslow, TG 2004, ‘A universal telomerase RNA core structure includes structured motifs required for binding the telomerase reverse transcriptase protein’ Proceedings of the National Academy of Sciences of the United States of America, vol. 101, no. 41, October, pp. 14713-14718, National Academy of Sciences pnas. 0405879101 viewed 10 September 2007, http://www. pnas. org/cgi/content/abstract/101/41/14713. Brown, J 2005, ‘What the Heck is an Enzyme’ Bugs in the News, viewed 10 September 2007, http://people. ku. edu/~jbrown/whatheck. html. Chappell, AS, Lundblad, V 2004, ‘Structural Elements Required for Association of the Saccharomyces cerevisiae Telomerase RNA with the Est2 Reverse Transcriptase’ Molecular Cell Biology, 24: 7720-7736. Chen, JL, Blasco, MA, Greider, CW 2000, ‘Secondary structure of vertebrate telomerase RNA’ Cell, 100: 503-514. Chen, JL, Greider, CW 2004, ‘An emerging consensus for telomerase RNA structure’ Proceedings of the National Academy of Sciences of the United States of America, vol. 101, no. 41, October, pp. 14683-14684, National Academy of Sciences pnas. 0406204101 viewed 10 September 2007, http://www. pnas. org/cgi/content/full/101/41/14683. Dandjinou, At, Levesque, N, Larose, S, Lucier, JF, Abou-Elela, S, Wellinger RJ 2004, ‘A phylogenetically based secondary structure for the yeast telomerase RNA’ Current Biology, 14: 1148-1158. Friedman, KL, Cech, TR 1999, ‘Essential functions of amino-terminal domains in the yeast telomerase catalytic subunit revealed by selection for viable mutants’ Genes Dev. 13: 2863–2874. Kelleher, C, Teixeira, MT, Forstemann, K, Lingner, J 2002, ‘Telomerase: biochemical considerations for enzyme and substrate’ Trends Biochem. Sci. 27: 572–579. Lai, CK, Miller, MC, Collins, K 2002, ‘Template boundary definition in Tetrahymena telomerase’ Genes Development, 16: 415–420. Lin, J, Ly, H, Hussain, A, Abraham, M, Pearl, S, Tzfati, Y, Parslow, TG, Blackburn, EH 2004, A universal telomerase RNA core structure includes structured motifs required for binding the telomerase reverse transcriptase protein’ Proceedings of the National Academy of Sciences of the United States of America, vol. 101, no. 41, October, pp. 14713-14718 Livengood, AJ, Zaug, AJ, Cech, TR 2002, ‘Essential Regions of Saccharomyces cerevisiae Telomerase RNA: Separate Elements for Est1p and Est2p Interaction’ Mol. Cell. Biol. 22: 2366–2374 Peterson, SE, Stellwagen, AE, Diede, SJ, Singer, MS, Haimberger, ZW, Johnson, CO, Tzoneva, M. Gottschling, DE 2001, ‘The function of a stem-loop in telomerase RNA is linked to the DNA repair protein Ku’ Nat. Genet. 27: 64–67. Shay, J, Zou, Y, Hiyama, E, Woodring, EW 2001, ‘Telomerase and cancer’ Human Molecular Genetics, vol. 10, no. 7, pp. 677-685. Skloot, R 2001, ‘The Marvels of Telomerase’ Hopkins Medical News, winter 2001, viewed 10 September 2007, http://www. hopkinsmedicine. org/hmn/W01/top. html. Tzfati, Y, Knight, Z, Roy, J, Blackburn, E H 2003, A novel pseudoknot element is essential for the action of a yeast telomerase, Genes Development 17: 1779–1788. Vermolen, BJ, Garini, Y, Mai, S, Mougey, V, Fest, T, Chuang, TCY, Chuang, AYC, Wark, L, Young, IT 2005, ‘Characterizing the Three-Dimensional Organization of Telomeres’ Cytometry, 67A: 144-150. Zapulla, DC, Cech, TR 2004, ‘Yeast telomerase RNA: A flexible scaffold for protein subunits’ Proceedings of the National Academy of Sciences of the United States of America, vol.

Infant Immortality Essay example -- essays research papers

Infant Mortality in the United States   Ã‚  Ã‚  Ã‚  Ã‚  Trends in infant mortality are considered to be a barometer of technology and an accurate indicator of the health of a society. Despite technological excellence and numerous social programs offered throughout the country, the infant mortality rate (IMR) in the United States continues to be a national concern. For many, â€Å"infant mortality† brings to mind the deprivation and poverty found in third world countries. Yet in the United States, nearly 40,000 children die every year for some of the same reasons that cause infant death in underdeveloped parts of the world (Anderson, 1987).   Ã‚  Ã‚  Ã‚  Ã‚  Infant mortality is prevalent in this country despite a richly developed and technologically advanced society. According to the Census Bureau, the IMR in the United States has dropped almost 66 percent in the past three decades (Eberstadt, 1991). In 1960, out of every thousand babies born, 26 died within their first year of life. By 1991, that number had dropped to less than nine out of every thousand babies (Eberstadt et al., 1991). According to the US Department of Health and Human Services (HHS), the US infant mortality rate in 1987 was higher than in 23 other countries or territories, including most of Western Europe, Hong Kong, and Singapore. The US infant mortality rate was about 20 percent higher than Norway’s, nearly 50 percent higher than in the Netherlands, and 200 percent higher than Japan’s (Eberstadt et al., 1991). The United States has not always fared so poorly in this international ranking. In the early 1950’s it ranked sixth best (Anderson et al., 1987).   Ã‚  Ã‚  Ã‚  Ã‚  The Select Committee on Hunger held a Congressional hearing on infant mortality in the United States on April 29, 1987. Representative Mickey Leland (D., TX), the committee’s chairperson, acknowledged the continued statistical improvements over the prior two decades. But he was very critical of the decline of the United States in the international ranking, expressing dismay that a country as wealthy and powerful as the United States should have an infant mortality rate worse than that of 16 other industrialized nations (Anderson et al., 1987). Through mediums such as this hearing and other forums, the federal government addresses this concern and establish... ...rson must strive to ensure that babies survive. No amount of technological skill can combat the preventative measures of proper prenatal care. The ultimate voice of prevention will only be heard by women who have enough maternal instinct to seek available prenatal and infant care. References   Ã‚  Ã‚  Ã‚  Ã‚  Anderson, G. (December 1987). Dying Young: Infant Mortality in the United States. America Press, Inc., 498-501.   Ã‚  Ã‚  Ã‚  Ã‚  Barnes-Boyd, C., Norr, K., & Nacion, K. (1996). Evaluation of an Interagency Home Visiting Program to Reduce Postneonatal Mortality in Disadvantaged Communities. Public Health Nursing Vol.13 No. 3, 201-208.   Ã‚  Ã‚  Ã‚  Ã‚  Eberstadt, N. (Fall 1991). America’s Infant-Mortality Puzzle. The Public Interest, No 105, 111-112.   Ã‚  Ã‚  Ã‚  Ã‚  March of Dimes Birth Defects Foundation. (1996). Birth Defects and Infant Mortality: A National and Regional Profile. Petrini, J. (Ed.).   Ã‚  Ã‚  Ã‚  Ã‚  Strobino, D., O’Campo, P., Schoendorf, K. (December 1995). A Strategic Framework for Infant Mortality Reduction: Implications for â€Å"Healthy Start†. The Milbank Quarterly Vol. 73 No. 4, 27.

Memorial Health System Essay

In going through the case study of the Memorial Health System CPOE Implementation it is apparent that the direction of the implementation was developing trouble from the onset of the proposal and the evaluation (Wager, Glaser, 2009). The first problem that is apparent is the lack of belief in the project. When the board approved the CPOE initiative and appointed the champions of the project the CEO Fred Dryer and CIO Joe Roberts there was already opposition from some of the stakeholders about this project. The physician believed the CPOE system would create more workload for them as well as this system reducing the physician to secretaries. To minimize the effect of this indicator a physician would have been appointed as a champion of this project to serve as an advocate of the system (Wager, Glaser, 2009). To gain buy-in from other physicians and user of the new system to ensure they have adequate input into the decision- making process (Wager, Glaser, 2009). The lack of clarity of purpose is apparent in this implementation. The project does not determine the scope and expectations clearly the board approved a multimillion dollar initiative to install an enterprise-wide clinician provider order entry system to reduce medical errors. To minimize this indicator the implementation team must determine the scope of the project and what the organization hopes the project will achieve (Wager, Glaser, 2009). A senior health care executive should meet with the implementation team to set the tone and communicate how the project relates to the organization’s strategic goals (Wager, Glaser, 2009). The team will determine the scope, establish expectations, and institute a project plan to minimize this indicator (Wager, Glaser, 2009). Insufficient leadership support is another indicator that played a part in the failure of this implementation. When leadership wants to hear positive communication about a project and not the negatives the project will fail. To minimize this  indicator clear and concise communication on the progress of the project is necessary the leader involve in the project should make time for reports on the progress of the implementation to handle any issues that may occur that could hinder the progress of the project (Wager, Glaser, 2009). Appointing people who believe and committed to the project into leadership position to lead the team and make time for communication from team and other leadership (Wager, Glaser, 2009). Another issue that was an indicator of failure to this project was the requirements analysis was rushed several key workflow and system integration issues were missed. To minimize this indicator a thorough requirement analysis is done to ensure that all workflow analysis to support the change in workflow and the system requirements analysis to ensure the requirements needed for the system to work are aligned with the strategic goals of the organization (Wager, Glaser, 2009). Budget cut to the project was a big indicator the would lead to failure of this project because in the status review meeting it was presented that the project was on scope, on schedule, and on budget led to leadership taking resources from the CPOE project. It is important the present a true picture of how the project is going not just what someone wants to hear (Wager, Glaser, 2009). Present a clear picture of how the budget is spent and what the project will continue to spend as the implementation goes to completion, such as training, or a newer version of the software (Wager, Glaser, 2009). Showing an account of the budget can help to minimize this indicator (Wager, Glaser, 2009). This project was doom from the beginning there was not a clear scope or the expectation of the project. Analysis were not done there was not a detail project plan plus and unrealistic time line for the project to be implemented. Leadership did not communicate enough to persuade the stakeholders who were against the project to change their thoughts and so on. However, for the project to work the objectives of the initiatives are clear and communicating these objectives and initiative, and test the degree to which the organizational members have brought into them. Dividing the project into manageable pieces address the complexity and test the evidence that the project may be at risk from trying to do too much all at once. Reference Wager, K. A., Lee, F. W., & Glaser, J. P. (2009). Health Care Information System: A practical approach for health care management (2nd ed.). San Frncisco, CA: Jossey-Bas.

The Great Gatsby By F. Scott Fitzgerald - 864 Words

Is it possible to repeat the past? Can one really recreate something that happened years before? According to Jay Gatsby in F. Scott Fitzgerald’s The Great Gatsby it is possible; and it has been done for the book The Great Gatsby itself. The Great Gatsby has been adapted into film many times by various directors; however, there are two that are considered most popular. The first really popular The Great Gatsby was Jack Clayton’s version that was released in 1974, and more recently Baz Luhrmann’s version that was released in 2013. Since the two movies are based on the same book, they have some of the same characteristics, but both movies are distinct. The two different movie directors make the movies distinct by: differences in how the characters are portrayed, the parties that are thrown, and the overall mood of the films. In Jack Clayton’s 1974 version of Fitzgerald’s The Great Gatsby, most of the characters are more relaxed and laid back, unlike Baz Luhrmann’s, which is full of vibrant and passionate characters. For example, Clayton’s version of Tom Buchanan is more of a solemn and quiet man, where Buchanan does not represent the bulking, attention-demanding polo player that Fitzgerald wrote about. The same goes for Tom’s mistress Myrtle, she is more reserved and comes off to the viewer as a pathetic housewife. Additionally, in Clayton’s movie adaptation, the main character himself is represented much differently. Robert Redford, who played Gatsby, took a much flatter andShow MoreRelatedThe Great Gatsby by F. Scott Fitzgerald1393 Words   |  6 PagesF. Scott Fitzgerald was the model of the American image in the nineteen twenties. He had wealth, fame, a beautiful wife, and an adorable daughter; all seemed perfect. 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