Re: Mutated brain gene: part of what makes us human

In article <f24qov$s1l$1@xxxxxxxxxxxxxxxxxxx>, Guy A Hoelzer <hoelzer@xxxxxxx>
wrote:
This is a very interesting statistic, although I don't really know what to
make of it yet. I want to point out, however, that this protein difference
number is not at all comparable to the DNA sequence difference number,
because the former represents amino acid strings while the later represents
individual nucleotides. For example, I'm sure that every human chromosome
(strings of nucleotides) has a different sequence than their homologous
chimp chromosomes. Does this mean that their DNA is 100% different? This
is the same logic that underpins the claim that 80% of the proteins are
different. Some would consider it impressive that 20% of the proteins are
identical along complete amino acid sequences. I would like to see the
comparison of amino acid identity between humans and chimps to compare with
the 99% nucleotide identity estimate between the same two species.

Problem is, protein identity is not terribly informative either. It is > 90%
pretty much across all mammals.

Amino
acid identities may be greater than 99%, despite having a difference of 80%
at the whole protein level.

And that's exactly the point! Very subtle differences can lead to very
significant outcomes. Many subtle changes combined almost invariably
produce very significant results.

DK

.

Relevant Pages

  • Re: Sean Pitman: definitions wanted
    ... >> protein sequences were far smaller than they are now. ... > in a sequence without a complete loss of function as long as it is done ... as well as minimum size and specificity requirements ... The mathematical properties of the specific random walk on the ...
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