BOTANY

BOTANY

EPIGENETICS

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Acetylation ____ access to the DNA, while methylation ____ access to the DNA.
A
allows, blocks
B
blocks, allows
C
does not change, inactivates
D
inactivates, does not change
Explanation: 

Detailed explanation-1: -It is well known that DNA methylation and histone deacetylation both repress gene transcription. When histones are acetylated, their electrostatic interactions with DNA become weaker, resulting in relaxed chromatin, which upregulates transcription; the opposite happens when histones are deacetylated by HDAC.

Detailed explanation-2: -DNA methylation is essential for silencing retroviral elements, regulating tissue-specific gene expression, genomic imprinting, and X chromosome inactivation.

Detailed explanation-3: -Acetylation removes positive charges thereby reducing the affinity between histones and DNA. Thus, in most cases, histone acetylation enhances transcription while histone deacetylation represses transcription, but the reverse is seen as well (Reamon-Buettner and Borlak, 2007).

Detailed explanation-4: -The answer appears to be DNA methylation. The promoters of inactive genes become methylated at certain cytosine residues, and the resulting methylcytosine stabilizes nucleosomes and prevents transcription factors from binding.

There is 1 question to complete.