Aging - AgingvsSenescence (cell,tissue organism) 1 2 3 4...

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Aging vs Senescence Disease  – malfunction of a system (cell, tissue,  organism) associated with particular symptoms   Aging  – normal developmental and chronological  process associated with getting older Senescence  – gradual decline in physiological  function at every level 1. Progressive 2. Endogenous 3. Deleterious 4. Irreversible
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Senescence and Evolution  (ultimate) Senescence as non-evolved Aging has no benefit to an organism (non- adaptive) Senescence as evolved (adaptive) 1. Co-evolution of senescence and sex Disposable soma theory 2. Variety of life span between species 3. Life span vs reproduction (declining  power of natural selection 4. Antagonistic pleiotropy (cost/benefit  tradeoffs)
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1. Senescence and Sex            Egg DNA    1/2             Germ Sperm ½ Germ + = Zygote     1 Somatic  Sexual reproduction (features) 1. Products are new varieties compared to original 2. Requires reductive division of genetic material 3. Requires Mixing of genetic material from two parents 4. Reproduction splits genetic lines (germ/soma)
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Paramecium have a choice Paramecium – two types of  nuclei Macronuclei – cell fission - leads to senescence Micronuclei – conjugation (sex) - no senescence **Paramecium have a “Disposable Soma” -  Disposable  soma theory  (aging) - organisms invest energy in  reproductive mechanisms over an infinite soma
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Disposable Soma Theory of  Aging Organisms must budget energy  priorities, including metabolism, growth,  activity and reproduction Increased energy budgeting towards  reproduction leads to decline in  maintenance functions (error checking,  damage removal)
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2. Variety of Lifespans: Programmed death correlates with strategies that  maximize energy use (niches) respond to environmental changes
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This note was uploaded on 05/23/2011 for the course BIO 101 taught by Professor Lanno during the Spring '08 term at Ohio State.

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Aging - AgingvsSenescence (cell,tissue organism) 1 2 3 4...

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