Human Growth and Development / Unit 15 HGD 2106 short lesson, about 20 seconds
Cellular Clock Theory
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The idea
Cellular clock theory holds that normal cells can divide only about forty to sixty times, the Hayflick limit, with telomeres, protective DNA caps, shortening at each division.
In practice
Progeria, a rare condition with short telomeres and a life expectancy of about thirteen, consistent with the theory.
Where people slip
Consistent with is not proof; no single theory of biological aging is conclusive, and causes probably combine.
Your place on the trail
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Builds on
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