quote:
We observe the same peptides and protiens in many species. Does it mean that these species are related?
In many cases, yes. Slight variations in the peptide sequence of the protein or the nucleotide sequence of the DNA will often have very little or no effect on the performance of the protein. Cytochrome c is an example; it has been demonstrated that an individuals cytochrome c gene can be replaced by another species' gene with no decrease in viability.
Funny thing is, despite all these genes being essentially the same in terms of functionality, the further apart two species are in terms of the standard phylogenic tree, the more different their cytochrome c genes are.
Interesting, no?
"The fact that a believer is happier than a skeptic is no more to the point than the fact that a drunken man is happier than a sober one." -- George Bernard Shaw