• Question: Why does DNA get too short at 120 years old, why not a different age?

    Asked by Purplepenguin to Carolyn, Peter, Richard, Sara, Siana on 18 Nov 2015.
    • Photo: Richard Unwin

      Richard Unwin answered on 18 Nov 2015:


      Hi purple Penguin,

      The ends of each piece of the DNA are very special sequences called ‘telomeres’.Every time a divides, it has to make a copy of it’s DNA. Every time it makes a copy, the way it does that means that it missed a tiny bit from the end, therefore these telomeres get shorter. Their role is to protect the ‘good stuff’ (i.e. the genes). However, at some point, the telomeres in a cell become too short and the cell dies. the number of divisions a cell can go through is different, depending on the cell (so it’s cell divisions that limits this, not time), but by the time we reach 120 we think there’s enough damage that we basically outlast our biological capacity to stay alive.

      Move to your additional question for more….

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