BIO 203 Although the chromatin structure of interphase and mitotic chromosomes is very compact, DNA-binding proteins and protein complexes must be able to gain access to the DNA molecule. Chromatin-remodeling complexes provide this access by ___.

Altering the extent of DNA supercoiling.

Explanation:

Chromatin Remodeling complexes provides access of transcriptional and regulatory activities to the DNA by changing the chromatin structure which is done by altering the extent of DNA supercoiling. Altering the extent of DNA supercoiling will give rise to a loose chromatin structure that the transcriptional and regulatory activities machinery can have access to. They include factors such as histone chaperones, histone modifying enzymes and ATP-dependent chromatin remodeling complexes.

Such mechanisms which the chromatin undergo include reconstruction: where nucleosomes undergo some compositional changes using special histone variants etc; enzyme induced covalent modification: which include acetylation, methylation, phosphorylation etc of histone tails; repositioning: such as histone chaperones mediating removal of histone from chromatin.

the answer would be 3

stimulus is a change in the environment that causes an organism to react. the response is the reaction to the stimulus. some examples of stimuli for zebras are drought, to many predators, and bad feeding grounds such as dead grass or plants. zebras respond to stimuli just like all other living organisms