Introduction to Genetic Analysis 548

Introduction to Genetic Analysis 548 - 547 17.1 The balance...

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Unformatted text preview: 547 17.1 The balance between cell loss and cell proliferation plest form, the normal regulation of cell numbers can be regarded as the interplay between mechanisms that con- trol cell proliferation and those that control cell death. Cell proliferation is controlled by the mitotic cell cycle, whereas cell death is achieved through a mechanism called programmed cell death, or apoptosis. In both cases, sequential biochemical events depend on the suc- cessful occurrence of prior events. In the cell cycle, fail- safe mechanismscalled checkpoints prevent the cell cycle from progressing until prior events have been suc- cessfully completed. Similarly, survival factors block ad- vancement of the death pathways. In multicellular ani- mals, there is community input into the decision-making process for these pathways. Sensor molecules (receptor proteins) interact with chemical signaling proteins pre- sent in the immediate external milieu of the cell. These protein signals and their sensors are wired into the ma- chinery of the cell cycle or apoptosis to act as either accelerators or brakes on one of these two pathways. The genetic basis of cancer is the disruption of these homeostatic mechanisms through mutations. Cancers are malignant tumors, exhibiting uncontrolled growth and, as they become more advanced, acquiring the abil- ity to metastasize spread throughout the body....
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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.

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