What is the "Death Clock"?
Solution
Dr. Hayflick has shown that we have another cause of aging. He has shown that we have a built-in death date of about 120 years, if diseases or accidents do not get us earlier. The point at which our cells have divided a fixed number of times sets this death date. It has been termed the “Hayflick limit.”
Our cells divide to produce new cells to replace the old cells damaged by metabolic ash build-up, free radicals, toxins, and other wear and tear mechanisms. As the cells divide, the chromosomes split to provide chromosomes for the new cells. When the chromosomes split, they lose part of their telomeres - the genes at their ends that keep the chromosomes organized. After a certain number of splits, the telomeres wear away and become too short to keep the chromosome organized and therefore the cell dies without being able to replace itself.
At birth, human telomeres are about 10,000 base pairs long, but by 100 years of age this has been reduced to about 5,000 base pairs.
You can think of telomeres as analogous to the plastic bands on the ends of shoelaces. Telomeres hold the important DNA code intact, preventing it from fraying as the molecules replicate over time.
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Article details
Article ID:
18
Category:
Why should I be concerned about longevity?
Date added:
2009-10-03 12:25:50
Views:
20
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