558 Chapter 17 • Genetic Regulation of Cell Number: Normal and Cancer Cells the S to G2 checkpoint, promotes apoptosis by attack-ing the integrity of the mitochondrion as well as by in-hibiting the expression of genes whose products con-tribute to survival. Why does it make sense that the cell cycle and apoptosis are linked? Simply put, the condi-tions that encourage proliferation also demand that the cell survives to duplicate itself. On the other hand, a cell with damage to its DNA poses a danger to the or-ganism itself. Thus, it is in the organism’s interest to have evolved mechanisms that not only block cell-cycle progression but also remove a mutated cell that might be on its way to becoming abnormal. 17.5 Cancer: the genetics of aberrant cell number regulation A basic article of faith in genetic analysis is that we learn a great deal about biology, both normal and diseased, by studying the properties of mutations that disrupt normal processes. It has certainly been true in regard to cancer. It has become clear that virtually all cancers of somatic cells
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This note was uploaded on 01/10/2011 for the course BIOL BIOL taught by Professor Johnson during the Spring '08 term at Aberystwyth University.