Epigenetic modifications change how the information in DNA is interpreted withou
ID: 260961 • Letter: E
Question
Epigenetic modifications change how the information in DNA is interpreted without changing the information itself, and can essentially be thought of as the process that regulates the structure of chromatin.
(A) (5 points) Define the two major types of epigenetic modifications.
(B) (10 points) Briefly discuss how each type of epigenetic modification from your answer in (A) is established, maintained, and reversed.
(C) (10 points) Describe the contribution of each type of epigenetic modification from your answer in (A) to chromatin structure, explicitly stating the nature of chromatin associated with active gene expression, and that associated with repressed gene expression
Explanation / Answer
1.The heritable alterations which are not due to the changes in the DNA, instead, which are due to the added tags to the DNA are called epigenetic modifications.
2.there are two types of epigenetic modifications, they are 1.DNA methylation and 2.Histone modifications.
3.In DNA methylation type of genetic modification, there will be a addition of methyl group to DNA.
4.Addition of methyl group to DNA alters the function of the genes and it even affects their expression.
1.5% of human DNA is methylated DNA only.
5.The most widely carried out DNA methylation is the addition of methyl group to the 5' Carbon of cytosine ring of the DNA. It results in the formation of 5-methyl cytosine.
6.The addition of methyl groups is done at several levels in cells. This addition of methyl groups to DNA is carried out by DNA methyl transferases.
7.A histone modification is a covalent post-translational modification to histone proteins of the DNA.
8. Histone modification includes methylation, phosphorylation, acetylation, ubiquitylation, and sumoylation.
9. Histone modification affects the chromatin structure, by affecting the wrapping of DNA around the histone octamers.
10. Histone modifications act in transcriptional activation/inactivation, chromosome packaging/DNA repair.
11. DNA methylation can be even reversed also, which is called demethylation of the DNA.
12. Demethylation of DNA is important in epigenetic reprogramming of genes.
13. Demethylation is important in disease mechanisms like cancer progression.
14. Demethylation occurs actively and passively.
15. DNA methylation and demethylation or hypomethylation gives cues of somany biological processes.
16. The quantification of 5'-mC provides information for detecting and analysing of somany diseases.
17.Histone acetylation occurs from acetyl coenzyme A by enzymatic addition processes.
18. The process of histone acetylation is involved in the regulation of many cellular processes.
19. The processes that are regulated by the acetylation of histones are transcription, gene silencing, cell cycle progression,DNA replication and DNA repair etc.
20. The DNA acetylation is carried out by DNA acetyl transferases.
21. Histone deacetylases remove the acetyl groups from the lysine residues of Histones.
22. if any imbalance occurs in histone acetylation process, it results in the formation of tumors, and followed by tumor progression.
23.Epigenetic modifications alter the accessibility of DNA , by which the gene expression pattern is changed.
24. The inheritance patterns also are affected by the epigenetic modifications.
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