How CpG Islands guides genes outside of NeoDarwinism


CpG dinucleotides in CpG islands are more likely to be methylated due to epigenetic mechanisms which can increase the rate of mutation. Methylation is a chemical modification that can be added to DNA by epigenetic enzymes. When cytosine is methylated, it becomes 5-methylcytosine (5mC). 5mC is more susceptible to deamination than unmethylated cytosine. It's a misnomer to call it a "mutation" as it's a cellular mechanism of "biased" mutations not a NeoDarwinian "random" mutation.

The high mutation rate of CpG dinucleotides is important for epigenetics. Epigenetic changes are changes in gene expression that are not caused by changes in the DNA sequence. Instead, they are caused by changes in the way that DNA is packaged and regulated.

One way that epigenetic changes can occur is through DNA methylation. When DNA is methylated, it can become less accessible to transcription factors, which are proteins that control gene expression. This can lead to a decrease in gene expression.

CpG dinucleotides are often methylated in regions of DNA that are not actively transcribed. This is thought to be a way of silencing genes that are not needed at a particular time or in a particular cell type.

When a CpG dinucleotide mutates, it is more likely to become unmethylated. This can lead to an increase in gene expression, which can reverse the epigenetic change.

In this way, the high mutation rate of CpG dinucleotides helps to ensure that epigenetic changes can turn genes on or off. These gene states can be passed on from cell to cell and from generation to generation. These CpG islands are in the gene promoters and guide but do not code for a protein. Being in the intrinsic DNA they are outside of the mutation model of NeoDarwinism that specifically works on the coding exonic DNA. Therefore epigenetic CpG islands are not a part of NeoDarwinism.

Epigenetics turn genes on and off without changing the gene.


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