Epigenetics - Wikipedia, the free encyclopedia


** Epigenetics **

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For the unfolding of an organism or the theory that plants and animals
(including humans) develop in this way, see epigenesis (biology). For
epigenetics in robotics, see developmental robotics.

In biology, and specifically genetics, *epigenetics* is the study of
heritable changes in gene activity that are /not/ caused by changes in the
DNA sequence; it also can be used to describe the study of stable,
long-term alterations in the transcriptional potential of a cell that are
not necessarily heritable. Unlike simple genetics based on changes to the
DNA sequence (the genotype), the changes in gene expression or cellular
phenotype of epigenetics have other causes, thus use of the term /epi-/
(Greek: /επί/- over, outside of, around) /-genetics/.^[1]

The term also refers to the changes themselves: functionally relevant
changes to the genome that do not involve a change in the nucleotide
sequence. Examples of mechanisms that produce such changes are DNA
methylation and histone modification, each of which alters how genes are
expressed without altering the underlying DNA sequence. Gene expression can
be controlled through the action of repressor proteins that attach to
silencer regions of the DNA. These epigenetic changes may last through cell
divisions for the duration of the cell's life, and may also last for
multiple generations even though they do not involve changes in the
underlying DNA sequence of the organism;^[2] instead, non-genetic factors
cause the organism's genes to behave (or "express themselves")
differently.^[3] (There are objections to the use of the term epigenetic to
describe chemical modification of histone, since it remains unclear whether
or not histone modifications are heritable.)^[4]

One example of an epigenetic change in eukaryotic biology is the process of

Source: en.wikipedia.org/wiki/Epigenetics

what are epigenetics

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