Darwin's DNA Polymerase "Random Mutations" just got "Ordered" by Epigenetics


DNA polymerase errors were once thought to be the source of neo darwinian variation, but we now know that epigenetics controls this. 

Epigenetics is typically the study of how gene expression can be altered without changing the underlying DNA sequence as with neodarwinism. This can be done through a variety of mechanisms, such as DNA methylation, histone modification, and non-coding RNA. However epigenetics can also direct biased “non random” mutations.

GC bias and Mutation bias are NonDarwinian mechanisms that make up 99% of mutations. NeoDarwinian DNA polymerase mutations make up <1%. However epigenetics controls this as well.

GC content is the percentage of guanine and cytosine nucleotides in a piece of DNA. GC bias is the tendency of certain regions of DNA to be more or less enriched in GC content. GC bias can be caused by a number of factors, including epigenetics.

Mutation bias is the tendency of certain types of mutations to occur more frequently than others. Mutation bias can be caused by a number of factors, including epigenetics.

Epigenetics can guide GC bias and mutation bias in a number of ways. For example, DNA methylation can silence genes that encode proteins that are involved in DNA repair. This can lead to an increase in the number of mutations in the DNA. Additionally, DNA methylation can affect the binding of transcription factors to the DNA. This can lead to changes in gene expression that can affect GC bias and mutation bias.

Here are some specific examples of how epigenetics guides GC bias and mutation bias:

  • DNA methylation can lead to GC bias. When a cytosine nucleotide is methylated, it is more likely to mutate to a thymine nucleotide. This is because methylated cytosine is a mismatched base with guanine. Over time, this can lead to an increase in the GC content of the DNA.

  • DNA methylation can lead to mutation bias. DNA methylation can silence genes that encode proteins that are involved in DNA repair. This can lead to an increase in the number of mutations in the DNA.

  • Histone modifications can lead to GC bias. Histones are proteins that package DNA into chromatin. Different types of histone modifications can affect the accessibility of the DNA to transcription factors. This can lead to changes in gene expression that can affect GC bias and mutation bias.

Epigenetic changes can be inherited from parents to offspring, and they can also be influenced by environmental factors. This means that epigenetics can guide the mutations that occur in DNA polymerase errors, making them more or less likely to be passed on to future generations.

For example, a study published in the journal Nature Communications in 2017 found that DNA polymerase errors in mice could be inherited by their offspring, and that these errors were more likely to be passed on if they occurred in regions of the genome that were already epigenetically silenced.

This suggests that epigenetics can act as a filter for DNA polymerase errors, determining which mutations are more likely to survive and be passed on to future generations. This challenges the neo darwinian understanding of how evolution works.

Here are some specific examples of how epigenetics can guide DNA polymerase errors:

  • DNA methylation: DNA methylation is a process in which methyl groups are added to DNA molecules. This can silence gene expression by preventing transcription factors from binding to DNA. DNA polymerase errors that occur in methylated regions of the genome are less likely to be repaired, and they are more likely to be passed on to future generations.

  • Histone modification: Histones are proteins that DNA wraps around. Histone modifications can change the structure of chromatin, which can affect gene expression. DNA polymerase errors that occur in regions of the genome where histones are modified in a way that silences gene expression are less likely to be repaired, and they are more likely to be passed on to future generations.

  • Non-coding RNA: Non-coding RNAs are RNAs that do not code for proteins. They can regulate gene expression in a variety of ways. For example, some non-coding RNAs can target DNA polymerase and prevent it from copying DNA accurately. This can lead to DNA polymerase errors, which can then be passed on to future generations.

Overall, the research on epigenetics and DNA polymerase errors is still in its early stages, but it is clear that epigenetics plays an important role in guiding DNA polymerase errors and shaping genetic variation. This challenges the neo darwinian understanding of how evolution works.

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