MCB 3211 Quiz: Cancer Cell Final
7 Mar 2017
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Once believed that dark clothing protected cells --made them live longer. Leonard hayflic proposed 60 doublings was the maximum number of doublings for a cell; after 60 doublings, the cell would undergo replicative senescence. Senecence - cell retires from doubling and expresses beta-galactosidase; can result from replication limit, oncogene activation, oxidative damage or other reasons. Quinescence- cell doesn"t devide for a short period of time; reversible stage of cell growth arrest. Oxygen can limit the doubling of cells. Embrionic stem cells can be immortal; cancer cells can be immortal. Shortening of telomeres limits the number of replications a cell can undergo; when telomeres become dangerously short, the cell enters crisis. Telomeres shorten because dna replication always begins with a primer; a primer that is removed; so 50-100 bps are lost ever time dna is replicated. Telomere erosion dna damage p51 and p21. Telomerase lengthening is done so by inactivated/incapacitated mmr. As cells age cdk inhibitors are activated.
