Genetics 101 by Beth Skwarecki

Author:Beth Skwarecki
Language: eng
Format: epub, mobi
Publisher: Adams Media

EPIGENETICS

The Environmental Mark

By now we’re used to thinking of DNA as a way of storing information. But the information that’s coded in the sequence of nucleotides (A, T, G, C) isn’t all. Your DNA also carries epigenetic information, which can change while the sequence of bases stays the same.

Epigenetics literally means “on the genome.” The cell can make changes by adding methyl groups (a carbon and three hydrogens) to certain parts of the DNA, or it can add other groups of atoms to specific places on the histone proteins that are snuggled up next to specific parts of the DNA.

These changes affect which parts of the DNA get transcribed into RNA, and thus they dictate what genes are expressed. Epigenetic modifications to the DNA are changes in gene expression that persist even when the DNA is replicated. When a cell divides, both copies end up with not just their parent cell’s DNA sequence, but also their parent cell’s epigenetic modifications: those methyl groups and histone tags that can continue to direct gene expression even after the cell divides.

These changes persist when a cell divides, but that doesn’t mean you inherited them from your parents. Before an egg and sperm meet, some of their epigenetic modifications are reset, so you get the chance to come up with your own. But we do know that some epigenetic changes seem to be heritable from parents to children. Just be aware that when we talk about epigenetics, that’s only one small piece of how they work.

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