AP BIOLOGY

Detailed explanation-1: -A common type of epigenetic modification is called DNA methylation. DNA methylation involves the attachment of small chemical groups called methyl groups (each consisting of one carbon atom and three hydrogen atoms) to DNA building blocks.

Detailed explanation-2: -DNA methylation involves the addition of a methyl or hydroxymethyl group to bases in the DNA sequence. The most commonly studied modification is the methylation of the C5 position on cytosine bases, or m5c (17, 18).

Detailed explanation-3: -Examples of epigenetics One example of an epigenetic change is DNA methylation-the addition of a methyl group, or a “chemical cap, ” to part of the DNA molecule, which prevents certain genes from being expressed. Another example is histone modification. Histones are proteins that DNA wraps around.

Detailed explanation-4: -The three main epigenetic marks are (1) histone modification, (2) DNA methylation, and (3) noncoding RNA, and each works in a different way to regulate gene expression.