so eventually they indneed very different from each other. so again :what make you think that all functional sequences can be reach from other functional sequence?
I never made that claim. All I have said is that genes that produce proteins with different functions can arise via copies of already existing genes mutating. I'd even say that's the most common way for new genes to form. I would never claim that it was the way all genes formed, so whether or not all genes could form that way is irrelevant.
it will be possible only if they exist near each other but we know that many are very diffierent in both structure and sequence.
1. I said that they USUALLY are physically close to each other in the sequence. Not always. When the replication mechanisms majorly mess up and duplicate entire sections of chromosomes or even entire chromosomes, the copies won't be physically near the original gene sequence at all.
2. I mentioned that as mutations build up, those genes derived from a copy of one will become less and less similar to their gene of origin. I never placed a limit to that; with enough time, genes that share origins can become so different that we wouldn't be able to recognize their shared origin.
3. You seem to be assuming that life started out with just 1 gene. This has no basis whatsoever, and evidence suggests the opposite, considering that the lipid bubbles in abiogensis experiments encapsulate many strands of RNA, not just 1, at a time.
as i said: he deal with small proteins and made some problematic assumptions like using only 2 kinds of amino acids instead of 20 or even 10 and deal only with bacteria.
Wow, he actually didn't do that. Rather, he suggested that his scope would cover functional protein regions that had a variety of less than 16 different amino acids. Most proteins don't contain all 20, which is also mentioned. He evaluated bacteria as the primary source of genetic variation in the history of the planet, which I agree is erroneous given that eukaryotes have very different mutation trends than bacteria do, but it only makes his scope of mutations over time smaller, not the number of functional regions possible. What limits that is the fact that we've discovered more functional regions between when that was published and now. Even so, if you thought this source was so fundamentally flawed, why'd you try to use it to begin with?
how you can make a fish tail to move by adding a single part?
Movement precedes being multicellular. The fish had most of the tools for motion long before being a multicellular organism; you are unintentionally subtracting parts that the fish started out with. But hey, if that single part is a muscle...