There are many mechanisms of epigenetics, including such as de/acetylation and methylation of histones, hyper methylation of CpG islands and phosphorylation etc. Epigenetics can be both spontaneous and hereditary, with some forms of epigenetics, such as histone acetylation, being passed on through gametes. Some forms of epigenetics have large consequences, leading to some serious conditions e.g. Prader-Willi syndrome, whilst some can have longer term ramifications for future generations e.g. Dutch hunger winter future generations. This essay will cover two main forms of epigenetics; Histone deacetylation and acetylation and DNA methylation, these have been chosen as they are amongst the most common forms of epigenetics and can have large consequences, for both individuals that acquired these changes and those who inherit them.
Histone are proteins which the chromatin wraps round to be packaged and therefore silence the transcription of the DNA. Histone modifications affect how tightly bound the DNA is to the histone, and depending on these modifications the level of silencing is affected. The enzymes …show more content…
The first two enzymes are DNA Methyl Transferase 3a and 3b (DNMT 3a and 3b), these two establish the methylation of the CpG islands for the first time. Then once the methylation has been established, DNMT1 maintains these methyl groups on the DNA during the DNA replication (Tollefsbol, 2010).
DMNT enzymes add methyl groups to the DNA by binding to the DNA, they then effectively turn the DNA double helix inside out exposing the base pairs, this is called ‘base flipping’, once the cytosine is exposed, a cysteine is used to nucleophilically attack the sixth carbon of the cytosine (C6), this transfers a methyl group from another molecule S-adenosyl-I-methionine, to the fifth carbon on the cytosine (C5), this creates 5-methyl cytosine (Zhang and Bruice,
Histone are proteins which the chromatin wraps round to be packaged and therefore silence the transcription of the DNA. Histone modifications affect how tightly bound the DNA is to the histone, and depending on these modifications the level of silencing is affected. The enzymes …show more content…
The first two enzymes are DNA Methyl Transferase 3a and 3b (DNMT 3a and 3b), these two establish the methylation of the CpG islands for the first time. Then once the methylation has been established, DNMT1 maintains these methyl groups on the DNA during the DNA replication (Tollefsbol, 2010).
DMNT enzymes add methyl groups to the DNA by binding to the DNA, they then effectively turn the DNA double helix inside out exposing the base pairs, this is called ‘base flipping’, once the cytosine is exposed, a cysteine is used to nucleophilically attack the sixth carbon of the cytosine (C6), this transfers a methyl group from another molecule S-adenosyl-I-methionine, to the fifth carbon on the cytosine (C5), this creates 5-methyl cytosine (Zhang and Bruice,