Question

QUESTION 18 Histone modifying enzymes (HATS, HDACs, etc) and chromatin remodeling complexes (SWI/SNF, etc) actively control gene expression. Their actions, in turn, are controlled by o Transcription Factors O DNA Polymerase o Histone H1 Mitochondria

Answer 1

Histone modifying enzymes are the class of enzymes that modify the histone residues. There are several modifications that are possible on the amino acids of the histone proteins. These modifications include acetylation, deacetylation, methylation, demethylation, etc. Apart from these there are other protein complexes called the chromatin remodeling complies. These bring about changes in the DNA. These changes include addition or removal of tags like acetyl, methyl, SUMOyl, etc.. These tags bring about modification in the expression pattern of the DNA.

Both these groups of enzymes control a diverse set of DNA expression patterns thereby leading to a wide range effect on the expression repertoire of the DNA.

However, these enzymes are themselves under strict control to ensure that they are turned on only in certain scenarios.

The controlling agents are called transcription factors, which undergo conversion between active and inactive states based on the stimulus. The stimulus could be internal like cell stress, DNA damage, etc. or external stimuli. Upon activating they bind to regions on DNA called enhancers, silencers, or promoters. Upon binding they can either recruit RNA Polymerase or make certain sites non-accesible for RNA Polymerase. Therey the expression pattern of these enzymes is controlled by the transcription factors.

Therefore, the correct answer is transcription factors.

asdfa