The genes that code for the positive cell-cycle regulators are called proto-oncogenes. Uncontrolled growth of the mutated cells outpaces the growth of normal cells in the area, and a tumor can result. ![]() Eventually, the pace of the cell cycle speeds up as the effectiveness of the control and repair mechanisms decreases. Over and over, small, uncorrected errors are passed from parent cell to daughter cells and accumulate as each generation of cells produces more non-functional proteins from uncorrected DNA damage. Even minor mistakes, however, may allow subsequent mistakes to occur more readily. The change in the cell that results from the malformed protein may be minor. All cancers begin when a gene mutation gives rise to a faulty protein that participates in the process of cell reproduction. If one of these changes to the DNA nucleotide sequence occurs within a gene, a gene mutation results. ![]() Even when all of the cell-cycle controls are fully functional, a small percentage of replication errors (mutations) will be passed on to the daughter cells. One of the critical processes monitored by the cell-cycle checkpoint surveillance mechanism is the proper replication of DNA during the S phase. Despite the redundancy and overlapping levels of cell-cycle control, errors occur. Explain how mutant tumor suppressors cause cancerĬancer is a collective name for many different diseases caused by a common mechanism: uncontrolled cell division. ![]() Describe how tumor suppressors function to stop the cell cycle until certain events are completed.Understand how proto-oncogenes are normal cell genes that, when mutated, become oncogenes.Explain how cancer is caused by uncontrolled cell division.By the end of this section, you will be able to:
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