Epigen

Epigenetics is the study of changes in organisms caused by modification of gene expression rather than alteration of the genetic code itself. Epigenetics has significant implications for understanding both genetic function and the nature of heredity.

Overview

Epigenetics is a subfield of genetics that studies changes in gene expression or cellular phenotype that do not involve alterations to the underlying DNA sequence. It includes any process that alters gene activity without changing the DNA sequence, and leads to modifications that can be transmitted to daughter cells (although experiments show that some epigenetic changes can be reversed). There may also be other ways of genome evolution.

History

The term "epigenetics" was first used by Conrad Waddington in 1942 to describe the interactions of genes with their environment, which bring the phenotype into being. In the 1970s, Robin Holliday and Arthur Riggs used it to describe DNA modifications that could be inherited.

Mechanisms

Epigenetic changes modify the activation of certain genes, but not the genetic code sequence of DNA. The microstructure (not code) of DNA itself or the associated chromatin proteins can be modified, causing activation or silencing. This accounts for why the differentiated cells in a multi-cellular organism express only the genes that are necessary for their own activity.

Epigenetic regulation

Epigenetic regulation is a process where genes are turned off or on, typically through chemical reactions. In biology, this is an important aspect of how cells differentiate to become different tissue types.

Epigenetic inheritance

Epigenetic inheritance is an unconventional finding. It goes against the concept that inheritance happens only through the DNA code that passes from parent to offspring. It implies that a parent's experiences, in the form of epigenetic tags, can be passed down to future generations.

See also

• Genetics
• Gene expression
• DNA methylation
• Histone modification

References

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