Evolution of the the Bacterial Flagellum

[pineapplebunnybounce]

The point of the precursor system being mentioned is that it shows that a system -like this one- is functional, if not for motility.

I understand that. Structures that were used for different purposes can be utilized in a different manner. In the case of flagellum, the proteins in the flagellum should be traced back to precursors that were providing a different functionality in the precursor bacteria. In order to prove that, you need to show that the flagellum proteins have homologs. If only 50% have homologs, what is your explanation for the other 50%? So the question is, how did those proteins evolve? How were they incorporated into the flagellum?

It's not really 50%. The blog assumes (and he honestly said that he did), that one of the structures did not evolve first. So proteins with homolog to that structure, he classified as no homolog. And he also quite honestly said that there was a paper that said that structure did evolve first. And the way he calculated the 50% was by counting amino acid lengths. What does that accomplish I really don't understand. Because a protein's homology to another affects the entire protein. Not individual amino acids. It would make more sense to say that we found homology for all the proteins except for these 15. So now we look for homology for these 15. There are 15 homology to look for, however long and short these 15 are, there is still only 15.

And why haven't they found homologous proteins. It's not easy to isolate all proteins in a bacteria, and then get their crystallized structure. it just isn't. the paper clearly stated "none yet known". If they had exhausted all the proteins they'll say they did not find any. It is a hypothesis isn't it? I'm not too informed about the flagellum debate thing, and i don't keep an eye on the research on this field. So yea, if they haven't been able to find all the homology, i would just wait and see. it's a pretty common thing to happen in science.

There is no need to come up with a new hypothesis yet. A hypothesis is proposed, and then it takes time to see if evidence supports it. So far evidence does. "None yet known" isn't sufficient to disprove a theory. It really just means they haven't found any yet, doesn't mean it doesn't exist. But since quite a lot has been found, to say that these do not exist and a new hypothesis is needed is a baseless assumption. And like cato said, i usually would look to what the authors suggest for their next steps, than to say, there are no next steps to be taken, this theory is in trouble. Took them 50 years to find higgs and no one said the theory was disproven, and hey they found higgs