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Why do protein coding genes have a forward mutation at least an order of magnitude greater than the reverse?

Most protein coding genes have a forward mutation rate (normal to mutant) that is at least an order of magnitude greater than the reverse mutation rate (Mutant back to normal). Why should this be the case?

1 Answer

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  • Anonymous
    9 years ago
    Favorite Answer

    Quite simply, any change to the normal gene causes a mutant.

    But to go from mutant back to normal, it takes a very specific reverse mutation.

    Take, for instance, the following DNA sequence: AAAA

    Any of the following "forward mutations" gives rise to a mutant: AATA, AACA, AAAG, GAAA, ATAA, etc...

    But to go from one specific mutant (e.g. AATA) back to AAAA, the T MUST revert back to a A.

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