Lec19 - Lecture 19 Eukaryotic Gene Regulation 1 Eukaryotic...

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Lecture 19 Eukaryotic Gene Regulation 1 Eukaryotic Genes Lodish 6th Ed. Chapter 7 Lodish 5th edition Chapter 11
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Eukaryotic Gene Regulation Regulatory Priorities Metabolic adjustment to nutritional environment. Higher eukaryotic organisms Development Cell differentiation Cell-to-cell communication “The right gene is activated in the right cell at the right time”
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All cells of a same organism contain an identical set of genes/DNA (few exceptions). Humans have about 22,000 genes Less than twice the number of genes in a fly (13,000) or in a worm (18,000) Two general types of genes: 1. Housekeeping genes (majority): Genes expressed in most cell types required for general cell functions and cell viability. (Ex: genes coding for all enzymes of basic metabolism and proteins used for cell structures such as the cytoskeleton and ribosomes) 2. Cell type-specific genes (fewer): Genes expressed in only particular cell types that perform functions specific of certain tissues. (Ex: genes coding for immunoglobulins/antibodies in B lymphocytes, growth hormone in somatotroph cells of the pituitary (brain), insulin in beta-cells of the pancreas, and albumin in hepatocytes of the liver)
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(both quantitative and cell type-specific) Post-transcriptional levels active protein Degraded mRNA Rapid response stimuli Transcriptional level (main switch) Transcription regulatory stimuli induce “slow” gene responses
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3 Different Classes of Eukaryotic Genes are Transcribed by 3 Distinct Eukaryotic RNA Polymerases Class I Genes are transcribed by: RNA polymerase I (Pol I) --> r RNA (18S , 5.8S, 28S) (ribosomal RNAs) Class II Genes are transcribed by: RNA polymerase II (Pol II) --> mRNA Class III Genes are transcribed by: RNA polymerase III (Pol III) --> Note: A fourth “single-polypeptide” nuclear RNA polymerase (sp-Pol IV) was discovered in 2005 consisting of a single protein; sp-Pol IV transcribes only a few speciFc mRNAs and is derived from alternative splicing of transcripts from the gene encoding the mitochondrial RNA polymerase
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1969 - Robert G. Roeder discovered the 3 eukaryotic RNA polymerases: Pol I , Pol II and Pol III Roeder, Robert G. Arnold and Mabel Beckman Professor The Rockefeller University Lasker Award 2003 Fractionation of nuclear extracts by chromatography on DEAE-Sephadex resin
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(yeast) 5 Common subunits to all three polymerases 16 12 14 Total Similarities and differences between prokaryotic and eukaryotic RNA polymerases Polymerase-specifc large subunits
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Eukaryotic Gene Promoters and Transcription Factors Promoter Enhancer (or Silencer) Core Promoter Elements Proximal Regulatory Elements Enhancer (or Silencer) Distal Regulatory Elements General (Basal) Transcription Machinery RNA polymerase (I, II, or III) + General/Basal Transcription Factors (TFI’s, TFII’s, or TFIII’s)
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Lec19 - Lecture 19 Eukaryotic Gene Regulation 1 Eukaryotic...

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