[...]
> I now believe, you are talking about doing for a living form what Yockey
> did for Cytochrome c (J. theor. Biol. 67(1977):345-376 and updated in his
Yes, that's right.
> book). The information content of a 101 amino acid protein, if you have to
> have a PARTICULAR sequence, has a high information content. And we can
> calculate this (which is what I was saying) But as Yockey showed for
> cytochrome, there are 10^93 sequences which will perform the function so
> the information required to specify A functional sequence is much less than
> the information required to specify A GIVEN sequence.
>
> Of course you are correct that we can only calculate an upper limit to the
> actual information required for a living form because we don't know all the
> functional sequences which are POSSIBLE to exist. (Which is what I think
> you were saying)
>
> Is this correct?
Yep. Looks like what I meant. Sorry if I shifted contexts without warning.
> I have made this criticism of the use of info theory that Thaxton, Bradley
> and Olsen display when they calculate the information content of A sequence
> of DNA from E.coli (Mystery of Life's Origins, p. 138). They assume that
> one and only one sequence of DNA makes an E. coli and of course there are
> billions of different sequences which work. Because of this, their energy
> calculation is a maximal limit, and the actual value is much much less.
Yes, constraints from "both directions" exist here--there are many ways
to code for a function, but not nearly as many as could exist in the
equivalent length of DNA. So there is sort of a squeeze there, and
figuring out how tight it really is is a very interesting open question.
Selectionists hope that the 'living space' is larger compared to the
sequence space, because that would give more fodder to natural selection.
They would be happier to see the 'functional space' smaller, so then
natural selection could 'thread the needle' into that functionality,
and it would prove that selection was the dominant force in evolutionary
history.
Non-selectionists, on the other hand, would like to see a larger functional
space, and a smaller 'living' space, to decrease the role of selection
and increase the role of chance, drift, etc. in determining evolutionary
history.
This is probably one of the most interesting interfaces between molecular
biology and evolutionary biology.
-Greg