Essential Elements of Biochemistry BCHM 3050 Dr Srikripa Chandrasekaran Lecture 3 13 15 Notes Regulation of Transcription I Regulation of gene expression in eukaryotes A Nucleus 1 Transcriptional Regulation of the histones Histones heterochromatin deacetylation removal of the Histones euchromatin acetylation attach the acetyl acetyl group X negative group positive 2 Histones are positively charged lysine and arginine primarily lysine contributes to this positive charge 3 Histones can undergo acetylation and methylation adding a methyl 4 Methylation and deacetylation promote heterochromatin 5 Acetylation and demethylation promote euchromatin 6 Methylation of DNA C CH3 methyl so C gets methylated 7 We are not born with these methyl groups they get accumulated over time by stress diet etc 8 Your DNA does not remain the same as you age adding methyl 9 groups can alter your DNA this falls under the study of epigenetics Identical twins start out the exact same but then they undergo different experiences throughout life that causes they to acquire methyl groups that differentiate them to a greater extent 10 The additional of these methyl groups can then affect our children as they can inherit our altered DNA 11 Methylation is a negative regulator of transcription 12 Acetylation of histones is a positive regulator of transcription II Histone modification 1 Histone modification 2 DNA modification methylation 3 Activators proteins binds to enhancers Activators are positive regulators of transcription Enhancers are the DNA sequences that bind to activator proteins Promoters are enhancers than generally bind to RNA polymerase RNA polymerase is an activator Promoters binding to RNA polymerase is positive regulation of transcription A The middle man is called a modulator that help enhancers and activators bind to each other when needed modulators are not always needed modulators are positive regulators of transcription activators are positive regulators of transcription 1 B DNA sequences called silencers are negative regulators silencers recruit repressors and this is negative regulation C RNA polymerase is a positive regulator D Modulators connect RNA polymerase with an activator E Silencer is a DNA sequence F Enhancers promoters silencers are DNA G Activators RNA polymerase repressors are proteins that bind to DNA 2
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