Question

1.Why is the epigenome considered our second genome?

2.How does epigenetics differ from traditional genetics? from epigenomics?

3.Explain how epigenetic events play a role in aging

4.Explain how epigenetic events control the formation of euchromatin and heterochromatin

5.Explain how epigenomics studies are conducted.

Please answer all questions in detail. Thank you

Answer 1

Epigenetics is termed as a, “ Studying gene function without changing sequences of DNA”. In a simple word, gene expression can be changed but DNA sequence is remain unchanged. Methylation is an event that is responsible for epigenetic changes. Here difference in the methylation pattern will influence the expression of several genes. Mostly this methylates regions are not coding for any genes (junk DNA ), but its methylation pattern will affects the expression of other genes. Hence epigenetic is called as your second genome.

   Addition of methyl group to the DNA sequences (especially CG rich region) makes the DNA sequence non functionals. These sequences cannot transcribed. Hence no protein is formed from this DNA sequences because DNA polymerase can not identify sequences for transcription. On the other side the coding regions are non methylated sequences cane be recognised by polymerase enzyme and it can be transcribed and translated into particular protein. Additionally, any variation in sequence of coding genes can altered its expression.

   Ageing is the process in which normal physiological and biological function of body decrease by time. Again makes the body more prone to disease like infection and cancer. Heterochromatic region of the genome is methylated and cannot code for any particular protein. However pattern of methylation will affects the expression of other genes. The methylation pattern is also responsible for cancer. Modification in Histon protein during methylation will also switch on and off effect for some genes. Histon modifications in heterochromatin and different level of methylation will be responsible for ageing.

   Euchromatin region can be code for protein. It is loosely packed DNA sequences in which histon molecules are loosely wrapped around it. In heterochromatic region DNA sequences are densely packed by histon specific methylation process which makes DNA inactive for transcription and translation. Heterochromatic region is junk DNA which cannot code for any protein.

   One can study the different methylation pattern in different conditions. Quantitative analysis of pistons can be useful in cancer study. Methylation specific PCR is the best tool for understanding how DNA methylation pattern may influence in gene expression and ageing.