Question

2. Understand the mechanism of action of steroid hormones. 3. Know the relationship between chromatin structure and gene expression 4. Know the effect of DNA methylation on gene transcription 5. Understand the role of insulators in gene expression. 6. Understand the common mechanisms of epigenetic regulation 7. Understand how RNA processing, stability and translation influence gene expression.

Answer 1

2. Mechanism of action for steroid hormones is to control/modulate gene expression, as hormone receptor bind to transcription factors which control the expression of batteries of gene.

3. Chromatin structure creates substantial obstacles for transcription which is primarily done by RNA polymerase II. RNA synthesis or transcription happen at the loose structure of DNA, which allow enzyme for synthesing of RNA. Therefore, all of the process which affact chromatin structure like histone modification, chromatin remodeling, histone variant incorporation, chromatin remodeling, histone eviction and histone variant incorporation, directly affect transcription.

4. DNA methylation leads to downregulation or suppression of gene, therefore reduce the abundance of the gene.

5. Insulators are cis regulatory regions on DNA of length 300bp to 2000 bp, present in multicellular eukaryotes. Insulator region of promoter contain multiple binding site for DNA binding protein. Also control the inter or intra interaction of chromosomal interactions, therefore, they regulate transcription or gene expression.

6. Epigenetic regulation involves both heritable and non-heritable DNA modifation which affect gene expression. These effect can be at individual level or heritable long term changes. These include majorly three types a. DNA methylation; b. histone-deacetylation, and c. micro-RNA expression. One of classical example of heritable epigetic regulation is a epigenetic modification in tomato, a Cnr mutation, which affect ripening of tomatoes, lead to yellow tomatoes instead of red.

6.