Archive for June, 2008
Sunday, June 1st, 2008
In eukaryotic chromosomes, individual molecules of DNA are several million base pairs long. Because these molecules are far too large to analyze directly, scientists are usually interested in cutting DNA into fragments of manageable size. Fortunately, for molecular biologists, bacteria have evolved a highly diverse set of enzymes, the “restriction ...
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Sunday, June 1st, 2008
In eukaryotes, the coding regions of most genes are not continuous. Rather, they consist of areas that are transcribed into mRNA, the “exons,” which are interrupted by stretches of DNA that do not appear in mature mRNA, the “introns”. The functions of introns are not known with certainty. A purpose ...
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Sunday, June 1st, 2008
The basic repeating units of the DNA polymer are nucleotides (Figure ). Nucleotides consist of an invariant portion, a five-carbon deoxyribose sugar with a phosphate group, and a variable portion, the “base.” Of
the four bases that appear in the nucleotides of DNA, two are purines, adenine (A) and guanine (G), ...
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Sunday, June 1st, 2008
Every gene consists of several functional components, each involved in a different facet of the process of gene expression (Figure) Broadly speaking, however, there are two main functional units: the “promoter” region and the “coding” region.
The promoter region controls when and in what tissue a gene is expressed. For example, ...
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Sunday, June 1st, 2008
The gene is the fundamental unit of inheritance and the ultimate determinant of all phenotypes. The DNA
of a normal human cell contains an estimated 50 to 100,000 genes, but only a fraction of these are used (or “expressed”) in any particular cell at any given time.1,2 For example, genes specific ...
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Sunday, June 1st, 2008
Cancer is a genetic disease. Abnormalities in genes that control cellular proliferation lead to the unrestrained growth that characterizes the malignant cell. Thus, to gain the initiative in cancer detection and treatment, oncologists must begin to understand the molecular roots of the disease: genes, their messenger RNAs, and the proteins ...
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Sunday, June 1st, 2008
In its fifth edition, Cancer Medicine has been named eponymously to honor its founding editors James F. Holland and Emil Frei III, two giants of medical oncology. The Holland-Frei Cancer Medicine reflects their dedication to innovative, comprehensive, and multidisciplinary care of cancer patients, as well as their belief in the ...
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