Monday, August 26, 2019

Telomeres and Tumors Paper Research Example | Topics and Well Written Essays - 2000 words

Telomeres and Tumors - Research Paper Example At one time, the DNA at the ends of chromosomes seemed to be static. Yet in most organisms that have been studied, the tips, called telomeres, are actually ever changing; they shorten and lengthen repeatedly† (Glieder and Blackburn). Since the past fifteen years, there have been remarkable findings, with respect to this change. Getting to the specifics, it has led to the discovery of theastonishing enzyme, telomerase that acts on telomeres and is considered a pre requisite for the maintenance of cancer in human being. Geneticists, Barbara McClintock, of University of Missouri at Columbia, and Hermann J. Muller, from the University of Edinburgh, are credited with having done extensive work on the intricate subjects of telomeres and telomerase. These scientists workedunconnectedly and with dissimilar organisms, however both of them realized that chromosomes were stabilized by a special component on their ends. â€Å"Muller coined the term telomere, from the Greek for end (telos) and part (meros). McClintock noted that without these end caps, chromosomes stick to one another, undergo structural changes and misbehave in other ways. These activities threaten the survival and faithful replication of chromosomes and, consequently, of the cells housing them.† (Glieder and Blackburn). ... â€Å"The observed heterogeneity led Blackburn, who had moved to the University of California at Berkeley, Jack W. Szostak of Harvard University and Janis Shampay of Berkeley to propose a new solution to what has been called the end-replication problem† (Glieder and Blackburn). â€Å"In 1972 James D. Watson, working at both Harvard and Cold Spring Harbor Laboratory, noted that DNA polymerases, the enzymes that replicate DNA, could not copy linear chromosomes all the way to the tip. Hence, the replication machinery had to leave a small region at the end (a piece of the telomere) un-copied.† (Glieder and Blackburn). Theoretically, if the cells were unable to reimburse for this fluke, chromosomes would decrease in their respective lengths, with each level of mitosis. The corrosion henceforth eradicating the telomeres and perilous genes in some group of the cells. The variations in the length of telomere, for the scientists, were an indicator that cells uphold telomeres at a constant size, or at least they try to. The telomeres decrease in length during mitosis, but their length also increases as freshly formed subunits attach themselves to them. â€Å"The researchers suspected that the source of these additional repeats was some undiscovered enzyme capable of a trick that standard DNA polymerases could not perform.† (Glieder and Blackburn). â€Å"When cells replicate their chromosomes, which consist of two strands of DNA twisted around each other, they begin by separating the double helix. The polymerases use each of these parentstrands as a template for constructing a new partner. The special enzyme the workers envisioned would be able to build extensions to single strands of DNA from scratch, without benefit of an existing DNA template.† (Glieder

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