Question

1. What is a CpG island, and how is it relevant to this topic?
2. List three distinct places/steps in gene expression that gene regulation can occur in eukaryotes (possibilities).

3 Define “chromatin remodeling’, “open chromatin” and “closed chromatin"

4.What is the SWI/SNF complex and what does it do?

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Answer 1

CpG islands are non- methylated gene markers present at 5' of the gene. The tag as the gene marker is all because of there role in the regulation of gene expression.

CpG islands can regulate chromatin structure.The methylation of CpG island can regulate(block it in closed form) the chromatin structure followed by gene regulation.CpG islands are the site for transcription initiation, methylation of CpG islands can inhibit translation.

Gene expression can be regulated at multiple stages like;

a. The chromatin structure can be controlled.

b. Transcription can be regulated.

c. m- RNA translation can be regulated.

3. Chromatin remodelling can be defined as a process which facilitates the transformation of the condensed form of chromatin into a relaxed form that facilitates transcriptional factors to approach the DNA and regulate gene expression. chromatin remodelling involves the conversion of nucleosome into an open system.

Open chromatin also known as euchromatin is a form of chromatin that lacks nucleosome and more accessible for the transcriptional factors and facilitate replication, transcription.

Closed chromatin is also known as heterochromatin is a condensed(tightly bound) form of chromatin contain nucleosome and can not be accessible for transcriptional factors.

4. SWI/SNF is a complex that regulate chromatin remodelling. These are ATP-dependent factors that open the condensed form of chromatin by depletion of nucleosome.This complex remodels the packaging of DNA.