Which statements about the modification of chromatin structure in eukaryotes are true? Select all that apply.

A. Deacetylation of histone tails in chromatin loosens the association between nucleosomes and DNA.

B. Acetylation of histone tails in chromatin allows access to DNA for transcription.

C. DNA is not transcribed when chromatin is packaged tightly in a condensed form.

D. Methylation of histone tails in chromatin can promote condensation of the chromatin.

E. Acetylation of histone tails is a reversible process.

F. Some forms of chromatin modification can be passed on to future generations of cells.

Ans.

Chromatin molecules are made up of DNA and histone proteins. Modification of chromatin structure include covalent, post-translational changes in histone proteins, present in chromation. Acetylation and methylation are two important histone modifications that affect structure of chromatin molecules.

Acetylation involves addition of an acetyl group to histones that increases transcription of DNA by loosen the association between DNA and nucleosome.

Methylation involves addition of a methyl group to histones that results in condensation of chromatin molecule and thus, decreases transcription of DNA.

Both acetylation and methylation are reversible processes.

Many chromatin modifications are genetic, means they can pass from one generation to another generation, called epigenetic modifications.

Thus, options B), C), D), E), and F).