![]() The hypothesis of epigenetic changes affecting the expression of chromosomes was put forth by the Russian biologist Nikolai Koltsov. Number of patent families and non-patent documents with the term "epigenetic*" by publication year.Ī definition of the concept of epigenetic trait as a "stably heritable phenotype resulting from changes in a chromosome without alterations in the DNA sequence" was formulated at a Cold Spring Harbor meeting in 2008, although alternate definitions that include non-heritable traits are still being used widely. However, its contemporary meaning emerged only in the 1990s. In scientific publications, the term epigenetics started to appear in the 1930s (see Fig. ![]() The term epigenesis has a generic meaning of "extra growth" that has been used in English since the 17th century. In other words, as a single fertilized egg cell – the zygote – continues to divide, the resulting daughter cells change into all the different cell types in an organism, including neurons, muscle cells, epithelium, endothelium of blood vessels, etc., by activating some genes while inhibiting the expression of others. During morphogenesis, totipotent stem cells become the various pluripotent cell lines of the embryo, which in turn become fully differentiated cells. ![]() One example of an epigenetic change in eukaryotic biology is the process of cellular differentiation. 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 instead, non-genetic factors cause the organism's genes to behave (or "express themselves") differently. Gene expression can be controlled through the action of repressor proteins that attach to silencer regions of the DNA. Further, non-coding RNA sequences have shown to play a key role in the regulation of gene expression. 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. The term also refers to the mechanism of changes: functionally relevant alterations to the genome that do not involve mutation of the nucleotide sequence. Such effects on cellular and physiological phenotypic traits may result from environmental factors, or be part of normal development. Epigenetics usually involves a change that is not erased by cell division, and affects the regulation of gene expression. ![]() The Greek prefix epi- ( ἐπι- "over, outside of, around") in epigenetics implies features that are "on top of" or "in addition to" the traditional (DNA sequence based) genetic mechanism of inheritance. In biology, epigenetics are stable heritable traits that cannot be explained by changes in DNA sequence, and the study of a type of stable change in cell function (known as a mark) that does not involve a change to the DNA sequence. ( September 2023) ( Learn how and when to remove this template message) Please help improve it to make it understandable to non-experts, without removing the technical details. This article may be too technical for most readers to understand.
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