Modifications of histone tails can: affect expression of some genes in response to the environment. affect chromatin structure. activate transcription of some genes. repress transcription of some genes. all of these choices are correct.

All of these choices are correct.

Explanation:

Histone modification can be defined as a type of gene expression regulation. It refers to covalent post-translational modifications of histon tail proteins such as methylation, phosphorylation, acetylation, ubiquitylation, and sumoylation. As a consequence of modifications, chromatin structure might be changed, into active regions of euchromatin, (active transcription), or heterochromatin regions (inactive transcription).

Modification might be due to response to the environment, are heritable and are called epigenetic control.

after a the power stroke, adp is released, but the cross-bridge formed is still in place. atp then binds to myosin, moving the myosin to its high-energy state, releasing the myosin head from the actin active site.