DNA methylation

For more information, log on to-
http://shomusbiology.weebly.com/
Download the study materials here-
http://shomusbiology.weebly.com/bio-m...
Source of the article published in description is Wikipedia. Thanks to original content developers.
Link- http://en.wikipedia.org/wiki/Main_Page
DNA methylation is a biochemical process involving the addition of a methyl group to the cytosine or adenine DNA nucleotides. DNA methylation stably alters the expression of genes in cells as cells divide and differentiate from embryonic stem cells into specific tissues. The resulting change is normally permanent and unidirectional, preventing one organism from reverting to a stem cell or converting into another type of tissue. DNA methylation is typically removed during zygote formation and re-established through successive cell divisions during development. However, the latest research shows that hydroxylation of methyl groups occurs rather than complete removal of methyl groups in zygote.[1][2] Some methylation modifications that regulate gene expression are heritable and cause genomic imprinting.

In addition, DNA methylation suppresses the expression of endogenous retroviral genes and other harmful stretches of DNA that have been incorporated into the genome of the host over time. DNA methylation also forms the basis of chromatin structure, which enables a single cell to grow into multiple organs or perform multiple functions. DNA methylation also plays a crucial role in the development of nearly all types of cancer.[3]

DNA methylation at the 5 position of cytosine has the specific effect of reducing gene expression and has been found in every vertebrate examined. In adult somatic cells (cells in the body, not used for reproduction), DNA methylation typically occurs in a CpG dinucleotide context; non-CpG methylation is prevalent in embryonic stem cells,[4][5][6] and has also been indicated in neural development.[7]