BCHM 4116 1st Edition Lecture 24Outline of Last Lecture I. Genes Transcribed of Gene Expression II. Transcription has 4 stages Outline of Current Lecture I. Regulation of Transcription and Regulation of Gene Expression Cont.II. Gene Transcription in Eukaryotes Current LectureChapter 29: Transcription and Regulation of Gene Expression cont. 3. Regulation of Transcription in Prokaryotesa. Operator: regulatory sequence lying adjacent to DNA being transcribed determines whether transcription takes placeb. Operons: transcriptional control regions & a set of related structural genes, all organized in a contiguous linear array along chromosome i. Expression of operon is determined by access of RNA pol to promoter and occupancy of operation by regulatory proteins influences this accessii. Induction activates transcription from promoter; repression prevents it c. Attenuation regulates transcription after it has beguni. Any regulation mechanism that manipulates transcription termination or transcription pausing to regulate gene transcription downstream4. 29.3 – Gene Transcription in Eukaryotesd. DNA of eukaryotes is wrapped around histones forming nucleosomese. Nucleosomes repress gene expressionf. Nucleosomes control gene expression by controlling transcriptional apparatusi. 2 classes of transcriptional co-regulators necessary to overcome nucleosome repression:1. Enzymes that covalently modify nucleosome histone proteins to loosen histone-DNA interactions2. ATP-dependent chromatin-remodeling complexesg. Transcription in Eukaryotes:h. The three classes of RNA polymerase in eukaryotes: RNA polymerases I, II, and III i. RNA pol I = localized to nucleolus & transcribes rRNAii. RNA pol II transcribes protein-encoding genes & mRNAThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.iii. RNA pol III – transcribes tRNA genes, rRNA genes, other small RNAsiv. ALL 3 RNA pol interact w/ their promoters via transcription factors 1. Transcription factors: DNA-binding proteins that recognize & accurately initiate transcription at specific promoter
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