The epigenome is made up of the marks or modifications made by chemical compounds on the genome in a cell. These marks or modifications are not part of the actual DNA instructions even though they can be passed on through cell division and reproduction. The epigenome consists of chemical compounds, either natural like those from food, or synthetic like those from pesticides or medicines. The epigenome interacts with DNA in several ways. The first way is through histone modification. Chemical tags or marks can tell histones how tightly to pack the DNA. If the histones wrap the DNA loosely, a hidden gene may become activated; if the DNA is wrapped tightly, a gene may become deactivated. The second way the epigenome can interact with DNA is through DNA methylation. This is where methyl groups attach to the helix-shaped DNA and interfere with genes causing them to turn on or off.
The epigenome can be modified by diet and/or exposure to chemicals because it is made up of chemical compounds. For instance, cancer can be caused by changes in the genome and epigenome by a methyl group attaching to a particular cell causing it to multiply rapidly into a tumor. Exposure to carcinogens like tobacco smoke or industrial fumes are linked to changes in the epigenome as well.
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