In article <9205071432.AA10616 at genbank.bio.net>
rbradbur at hardy.u.washington.edu (Robert Bradbury)
>> This means by the time you hit 80, your mutation frequency is
> 2.2 x 10^-5 in a single gene. Multiply by 5000 active
> genes per cell and you have 1 in 10 cells with a broken gene...
>> Hmmmm, so damaging .2% of a gene makes it non-functional. Due to the
> degenerate code from DNA to proteins and the large portions of proteins
> which aren't critical to structure/function you can make a case that a
> large fraction of the DNA for a protein can be damaged without harming the
> protein. ...
>> If we say that 10x the critical active area is important for
> general functioning then every cell in the body has a gene suffering a
> loss of function due to DNA damage!
If the DNA coding sequences really are redundant, wouldn't you divide
the mutation frequency by 10 instead of multiplying it by 10? If so,
then by age 80 only 1 in 100 cells would be suffering loss of function
due to DNA damage. This defect rate appears to be too low to account
for the effects of aging.
I'll assume that either I misunderstood the article or that there
is a mistake somewhere. What's wrong?
- Larry French
