For decades, scientists have known the basic structure of our DNA, the building blocks that make up our genes. Although nearly every cell in the human body has the same set of genes, why is it that different types of cells, such as those from brain or skin, look and behave so differently?
The answer is epigenetics, a rapidly growing area of science that focuses on the processes that help direct when individual genes are turned on or off. While the cell’s DNA provides the instruction manual, genes also need specific instructions. In essence, epigenetic processes tell the cell to read specific pages of the instruction manual at distinct times.
Some epigenetic changes are stable and last a lifetime, and some may be passed on from one generation to the next, without changing the genes.
Several epigenetic processes involve chemical compounds that attach, or bind, to DNA or to proteins that package the DNA within cells called histones. When a chemical compound binds to DNA, certain genes switch on or off, selecting which proteins are made.
For example, the epigenetic process of DNA methylation involves the binding of a chemical compound called a methyl group to certain locations on the DNA. This binding changes the structure of DNA, making genes more or less active in their role of making proteins.