Question

A)Describe the mechanism of epigenetic modification and why it affects whether a given gene is available b)how does this differ from the mechanism of evolution?

Answer 1

A) Epigenetics refers to all heritable changes in general expression which are not coded in general sequence. These can be both mitotic and meiotic. It acts through 4 mechanisms:

DNA methylation: these are modifications at DNA level which are cancelled out during the process of gametogenesis. Hence it is not inherited

Chromatin remodelling: implies shifting of neucleosome cores. This is a major factor controlling Gene expression by induction and repression.

Histone modification: transcription due to modifications in histone.

RNA interference: Epigenetics modifications due to presence of non-protein coding RNAs.

It affects an available Gene in the way it expresses. There's no physical change in DNA sequence but the expression of the gene changes.

b) These Epigenetic modifications are not usually heritable. Hence in every generation, there is no connection with the modification of the previous generation. Hence it is not a continuous process. Whereas in evolution, the changes are heritable and it is a continuous process. However, if Epigenetic modifications are heritable, it leads to evolution.