What is epigenetics?
Epigenetics, literally “on” genes, refers to all modifications to genes other than changes in the DNA sequence itself. Epigenetic modifications include addition of molecules, like methyl groups, to the DNA backbone. Adding these groups changes the appearance and structure of DNA, altering how a gene can interact with important interpreting (transcribing) molecules in the cell’s nucleus. How do epigenetic modifications affect genes? Genes carry the blueprints to make proteins in the cell. The DNA sequence of a gene is transcribed into RNA, which is then translated into the sequence of a protein. Every cell in the body has the same genetic information; what makes cells, tissues and organs different is that different sets of genes are turned on or expressed. Because they change how genes can interact with the cell’s transcribing machinery, epigenetic modifications, or “marks,” generally turn genes on or off, allowing or preventing the gene from being used to make a protein. On the other h
The study of these modifications—what they are, how they are laid down, and the processes that they control—is the field of research known as epigenetics. An epigenome is the description of these modifications across the whole genome, but unlike the genome DNA sequence, each organism has multiple epigenomes—for example, in different cell types—that may change during its lifetime in response to environmental cues.
Epigenetics is a term which is used to describe situations in which genes express themselves differently, although the underlying DNA is the same. For example, if a calico cat is cloned, the clone will not look physically identical, despite the fact that their genetic code is the same. This is because the expression of genes is influenced by epigenetics. One could think of the genome as a book of blueprints, laying out a number of options in the form of genes. The epigenome is like the contractor who goes through the book, deciding which options to include in a house. Two different contractors can build radically different houses from the same book of blueprints, in the same way that two organisms with identical DNA can look very different. Epigenetics plays an important role in the development of living organisms. When an egg and sperm cell first meet to form a zygote and start replicating, epigenetics comes into play, telling the cells what to develop into. Hair and skin cells, for e
