Today, that is the precise definition of epigenetics: the molecular
factors that regulate how DNA functions and what genes are turned on or
off, independent of the DNA sequence itself. Epigenetics involves a
number of molecular processes that can dramatically influence the activity of the genome without altering the sequence of DNA in the genes themselves.
One of the most common such processes is ‘DNA methylation’, in which molecular components called methyl groups (made of methane) attach to DNA, turning genes on or off, and regulating the level of gene expression. Environmental factors such as temperature or emotional stress have been shown to alter DNA methylation, and these changes can be permanently programmed and inherited over generations – a process known as epigenetic transgenerational inheritance.
Another major epigenetic process discovered in recent years is ‘histone modification’. Histones are proteins that attach to and alter the structure of DNA, which in turn wraps around the histones like beads on a string. The combination of DNA and histone together has been called ‘chromatin structures’ – and the coils, loops and twists in chromatin structures in response to environmental stress can permanently alter gene expression as well.
More recently, researchers have documented ‘RNA methylation’ in which methyl groups attach to the genetic helper molecules, in the process altering gene expression and subsequent protein production for generations down the line. Likewise, the action of so-called ‘non-coding RNA’, small RNA molecules that bind to DNA, RNA and proteins, also alter the expression of genes, independent of DNA sequence.
All of these epigenetic mechanisms are critical and have unique roles in the molecular regulation of how DNA functions. The regulation of biology, it follows, will never involve a ‘genetic-only process’, nor an ‘epigenetic-only process’. Instead, the processes of epigenetics and genetics are completely integrated. One does not work without the other.
- Darwin’s theory that natural selection drives evolution is incomplete without input from evolution’s anti-hero: Lamarck
One of the most common such processes is ‘DNA methylation’, in which molecular components called methyl groups (made of methane) attach to DNA, turning genes on or off, and regulating the level of gene expression. Environmental factors such as temperature or emotional stress have been shown to alter DNA methylation, and these changes can be permanently programmed and inherited over generations – a process known as epigenetic transgenerational inheritance.
Another major epigenetic process discovered in recent years is ‘histone modification’. Histones are proteins that attach to and alter the structure of DNA, which in turn wraps around the histones like beads on a string. The combination of DNA and histone together has been called ‘chromatin structures’ – and the coils, loops and twists in chromatin structures in response to environmental stress can permanently alter gene expression as well.
More recently, researchers have documented ‘RNA methylation’ in which methyl groups attach to the genetic helper molecules, in the process altering gene expression and subsequent protein production for generations down the line. Likewise, the action of so-called ‘non-coding RNA’, small RNA molecules that bind to DNA, RNA and proteins, also alter the expression of genes, independent of DNA sequence.
All of these epigenetic mechanisms are critical and have unique roles in the molecular regulation of how DNA functions. The regulation of biology, it follows, will never involve a ‘genetic-only process’, nor an ‘epigenetic-only process’. Instead, the processes of epigenetics and genetics are completely integrated. One does not work without the other.
- Darwin’s theory that natural selection drives evolution is incomplete without input from evolution’s anti-hero: Lamarck
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