Regulation of Gene Expression PDF

Regulation of Gene Expression Part 2  Learning Outcomes 1.List the processes that are controlled by 8.Describe how chromatin structure can be differential regulation of gene expression in modified by the chromatin remodeling multicellular eukaryotes...

Regulation of Gene Expression Part 2  Learning Outcomes 1.List the processes that are controlled by 8.Describe how chromatin structure can be differential regulation of gene expression in modified by the chromatin remodeling multicellular eukaryotes complex and how chromatin remodeling 2.Describe the structure of a transcription factor, affects gene expression and be able to identify three major classes of transcription factor DNA-binding domains 9.Describe how DNA methylation by DNA methyltransferases regulate gene expression 3.Define combinatorial control of gene expression and explain its role in regulation of gene expression 10.Explain how alternative splicing can lead to alternative mRNAs, and predict possible 4.Characterize and name the transcription factor splicing products from a eukaryotic gene DNA binding sites based on their distance from the transcription start site 11. Contrast global and specific translational 5.Describe the role of coactivators and control, and give describe examples of each corepressors in mediating the effect of transcription factors on gene expression, and list examples of 12. Describe the mechanisms of protein each modification and selective degradation by 6.Explain the role of the mediator protein complex proteasome and explain how these processes in regulating transcription regulate gene expression at the post- 7.Characterize the mechanism by which histone translational level. acetyltransferases (HATs) and histone deacetylases (HDACs) regulate gene expression 13. Predict at which level a gene is regulated  Mechanism of Gene Regulation in Prokaryotes and Eukaryotes In prokaryotes the primary control point is the process of transcription initiation In eukaryotes expression of gene into proteins can be controlled at various locations. 3 Check Points for Gene Expression in Eukaryotes o Synthesis of proteins is controlled right from the chromatin stage. o Expression of gene is controlled at many steps during the process of transcription and translation. o Description of the control points is dealt in detail in the subsequent slides. 4  Zinc finger motif TF III A, a positive regulator of 5S RNA gene transcription requires Zinc for activity. It contains nine Zinc ions in a repeating coordination complex closely spaced to the cysteine-cysteine residues followed by 12- 13 amino acids and later by a histidine- histidine pair. Zinc is coordinated by two cysteine and two histidine residues. The protein containing zinc fingers lie on the face of DNA helix. Zinc finger motif Chromatin Structure Two forms of chromatin o Euchromatin – A lesser coiled transcriptionally active region which can be easily accessed by the RNA polymerases. o Heterochromatin – A highly condensed transcriptionally inactive region. The genes in this region cannot be accessed by the RNA polymerases for active transcription. 22  Chromatin Structure Mechanisms which affect the chromatin structure and hence the expression of gene are: 1. Histone modifications – These modifications make a region of gene either transcriptionally active or inactive. a)Acetylation ↑Acetylation ----↓ Condensation of DNA ----- ↑ Transcription of genes in that region 23