BIOL 2P92 Lecture Notes - Dna Mismatch Repair, Pleiotropy
19 Jan 2013
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And yet, longer life spans have not evolved. Given that organisms are capable fo constructing themselves from scratch, they should also be capable of maintaining their organs and tissues once formed. Organisms do have remarkable abilities to replace or repair damaged parts; yet in many organisms repair is incomplete. Under the evolutionary theory of senescence, the failure to completely repair damage is ultimately caused by either : deleterious mutations, trade-offs between repair and reproduction. Deleterious mutations and aging: the mutation accumulation hypothesis. Many mutations causing death are highly deleterious. A mutation causing death at age 2, would be selected against strongly. What kind of mutation would cause death, but only at an advanced age: one possibility is a mutation that reduces an organism"s ability to maintain itself in good repair. Germ-line mutations in dna mismatch repair genes cause a form of cancer in humans called hereditary nonpolyposis colon cancer.
