>
> >Walt Hicks wrote:
> >
> >This 99% has always confused me in that is is a number that has been
> >quoted for many years. Yet, it is my understanding that neither the
> >chimpanzee nor human genome have been mapped to anywhere this degree of
> >completeness. So what does this 99% mean? (I'm not arguing; I just don't
> >understand.)
>
> The two genomes are approximately 99% identical in what has been mapped thus
> far. That is my understanding.
>
> Another good question for Francis Collins.
I think it has been measured in terms of human-chimp DNA hybridization.
You heat up a sample with human and chimp DNA, and the strands of DNA
separate from one other, forming single-stranded human and chimp DNA. You
cool down the sample and you will have some hybrid human-chimp
double strands. Now you measure how much heat you need to separate the
hybrid DNA. This temperature is proportional to how similar the sequences
are (number of nucleotide mismatches). This tool has been used a lot in
the early days of molecular systematics, when direct sequencing was much
harder.
Marcio
This archive was generated by hypermail 2b29 : Mon Mar 25 2002 - 15:09:07 EST