DNA Methylation is the act of adding methyl groups to a certain molecule. In most cases methylation happens to a DNA molecule which can affect how DNA is expressed. A methyl group consists of one central carbon with three hydrogen bonded to the central carbon with hydrogen bonds.
Dna methylation in vertebrates typically occurs at CpG sites ( cytosine -phosphate-guanine sites). Cytosine is directly followed by guanine in the Dna sequence. Methylation results in the conversion of the cytosine to 5- methyl cytosine. The formation of Me- CpG is catalysed by the enzyme Dna methyl transferase it is believed to be the primary enzyme responsible for copying methylation patterns after DNA replication.
Image source credit -https://pubs.niaaa.nih.gov/publications/arcr351/6-16.htm
Image source credit-https://www.elitenetzwerk.bayern.de/elitenetzwerk-home/forschungsarbeiten/lebenswissenschaften/2011/zillner-forschungsbericht0/
Gene switched off means - The chromatin is condensed(silent ) and methylated cytosines .
Dna methylation in vertebrates typically occurs at CpG sites ( cytosine -phosphate-guanine sites). Cytosine is directly followed by guanine in the Dna sequence. Methylation results in the conversion of the cytosine to 5- methyl cytosine. The formation of Me- CpG is catalysed by the enzyme Dna methyl transferase it is believed to be the primary enzyme responsible for copying methylation patterns after DNA replication.
Image source credit -https://pubs.niaaa.nih.gov/publications/arcr351/6-16.htm
Function-
The main function of DNA methylation is to silence gene expression. The methyl group binds to the DNA at either position ( adenine or cytosine) molecules of the DNA strand. This allows the methyl group to integrate itself into the DNA strand, tightening the strand closer together. The strand being tightened causes certain genes to be muted. When a gene is silenced, the gene willl not be expressed.
Image source credit-https://www.elitenetzwerk.bayern.de/elitenetzwerk-home/forschungsarbeiten/lebenswissenschaften/2011/zillner-forschungsbericht0/
Gene switched off means - The chromatin is condensed(silent ) and methylated cytosines .
Biological functions of DNA methylation-
- Transcriptional gene silencing
- Genome stability
- Chromatin compaction
- Genome defense
- Suppression of homologous recombination between repeats
- X chromosome inactivation (females).
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