Normal users can only vote to migrate to sites which have graduated, but moderators can.
Out of your examples, all the sites are in Beta except Chemistry.SE, so I think it could be added but there is also a close reason that states "General chemistry questions are off topic...." and redirects the OP to Chem.SE
A similar question was also asked before.
Whilst the molecules in question are obviously very important in biology, I saw no biological context in either the question or the answer. With that in mind I applied our guidelines for questions about bio-informatics (requiring a clear biological context) and moved it across to Chemistry, where it has gained another answer.
I did glance at how much rep ...
The question is about the chemistry of a molecule that is very important in biology. It is in the overlapping area between the chemistry and the biology site, and would be on-topic on both of them, in my opinion.
In general, I think we should not migrate questions in this overlapping area unless the author asks us to.