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Cell Death - older cells have shorter telomeres o telomere...

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Cell Death programmed cell death - cells between fingers/toes die 1/2 of neurons created never make connections, eventually die required for proper development necrosis - cells that die due to injury, releases contents into extracellular fluid apoptosis - cell programmed to die shrink/shrivel, remains taken up by other cells bax proteins starts apoptosis by binding to permeable pores of mitochondria bcl-2 prevents cell death by preventing damange from free radicals (highly reactive atomic fragments) antioxidants - proteins, other molecules that destroy free radicals aging theories - puberty is safest time to live accumulated mutation hypothesis - oldest general theory about aging o accumulation of mutations >> lethal death o OH group tends to be added to guanine base as cells age o effects of radiation-induced mutations after Hiroshima/Nagasaki bombings show no correlation between aging and mutations telomere depletion hypothesis
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Unformatted text preview: - older cells have shorter telomeres o telomere- repeated TTAGGG sequence o portion of telomere cap lost w/ each replication o cancer cells avoid telomeric shortening o adding to telomeric caps increased number of times cells could perform DNA replication • wear-and-tear hypothesis- cells wear out, get damaged through age o damage over time limits cell’s ability to work properly o free radicals - atomic fragments containing an unpaired electron, produced by oxidative metabolism, can damage cells o glycation- process that causes glucose to link to proteins, reducing flexibility • gene clock hypothesis- people over 100 years of age more likely to have mutated C150T mitochondrial DNA o Werner’s syndrome - causes premature aging, found on chromosome 8, affects helicase enzyme in DNA repair • current aging theories- still no true mechanism for counting o connection found between aging, signaling from insulin-like receptors...
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