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BoC studyguide - MCDB 23 David Kohl Biology of Cancer Fall...

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MCDB 23 David Kohl Biology of Cancer Fall 2007 Review Sheet Nature of cancer: 1) They are growing faster than they are dying off , and are less subject to the controls of normal cells. There are several places in the cell cycle where this can occur; basically they can multiply faster, age more slowly, and/or not die off as quickly. Although it is very common to say so, it's not technically factual to say that cancers grow in an "uncontrolled" way. Many tumors grow more slowly than some other normal tissues. No tumor grows nearly as fast as an embryo or the lining of the intestine, for example. (The intestinal lining grows quickly and also is sloughed off at a rapid rate.) 2) They invade normal tissue , eventually compromising the function of the organ in which they begin. This may happen very slowly or more quickly, depending on the aggressiveness of the tumor. 3) They metastasize - cells travel through blood, lymph, or body cavities to remote locations in the body. The vast majority of these cells die, but some may begin multiplying to form a new tumor. Wherever the metastasis is, it retains the characteristics of the original tumor - for example, uterine cancer would stay uterine cancer even if it spreads elsewhere. 4) They are genetically abnormal and unstable. The cells tend to have large nuclei with extra chromosomes, and produce more mutations over time. 5) Tumors are less well-organized than the organs in which they arise. The architecture of a tumor is much less specialized, and the cells don't work as well together as that of a normal organ. Also, they contribute nothing to the functioning of the body as normal organs do. Comparison of cancer cell vs. normal cell: Normal cells- Reproduce themselves exactly. Stop reproducing at the right time. Stick together in the right place. Self-destruct if they are damaged. Become specialized or 'mature'. Cancer cells- They carry on reproducing . They don't obey signals from other neighboring cells . They don't stick together . They don't become specialized, but stay immature . They don't die if they move to another part of the body Process of carcinogenesis – i.e. multiple mutations: cells have safeguarding and growth- promoting systems. If the genes that specify these proteins are compromised, the systems in which they participate can malfunction, contributing the development of a cancer cell. Both the systems must be compromised (multiple mutations) for cancer to develop. Metastasis- When cancer spreads to other organs of the body. Pieces of a malignant tumor break off from the main one and travel through the circulatory system to different sites of the body. Cell cycle – normal and abnormal
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Proto-oncogenes and oncogenes : genes that tell a cell to enter the cell cycle and control when a cell should divide. If a proto-oncogene loses the ability to regulate the cell cycle, the cell may divide uncontrollably. Proto-oncogenes can become damaged and become a cancer gene (oncogene). Tumor suppressor genes-
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BoC studyguide - MCDB 23 David Kohl Biology of Cancer Fall...

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