Regulation of gene expression in prokaryotes Katalin Kiss Dept. of Medical Biology 12.11. 2007.
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Transcript of Regulation of gene expression in prokaryotes Katalin Kiss Dept. of Medical Biology 12.11. 2007.
![Page 1: Regulation of gene expression in prokaryotes Katalin Kiss Dept. of Medical Biology 12.11. 2007.](https://reader034.fdocuments.net/reader034/viewer/2022051517/56649ed35503460f94be429d/html5/thumbnails/1.jpg)
Regulation of gene expression in prokaryotes
Katalin Kiss Dept. of Medical Biology
12.11. 2007.
![Page 2: Regulation of gene expression in prokaryotes Katalin Kiss Dept. of Medical Biology 12.11. 2007.](https://reader034.fdocuments.net/reader034/viewer/2022051517/56649ed35503460f94be429d/html5/thumbnails/2.jpg)
Gene expression in prokaryotes
• Types of expression:– Constitutive expression (eg. genes of glucose
utilizing enzymes)– Regulated expression
• induction (eg. genes of catabolic enzymes)• repression (eg. genes of biosynthetic enzymes)
• Significance of regulation: adaption to changes in enviroment (eg. nutrient supply), „feedback”
• Level of regulation during gene expression: mostly transcription (activity of RNA polymerase) is regulated
• Mechanism of regulation: operon model
![Page 3: Regulation of gene expression in prokaryotes Katalin Kiss Dept. of Medical Biology 12.11. 2007.](https://reader034.fdocuments.net/reader034/viewer/2022051517/56649ed35503460f94be429d/html5/thumbnails/3.jpg)
Operon model
Francois Jacob and
Jacques Monod
(Nobel-prize 1965.):Study of E.coli bacterium
Regulation of gene expression at the level of transcription
Operon theory
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Operon
Components:– Regulated genes = structural genes
(transcribed as a polycystronic mRNA)– Promoter– Operator
Types:– Inducible– Repressible
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Regulatory elements of operon
• DNA sequences = „cis-acting elements” (operator, promoter)
• Regulatory proteins = „trans-acting elements” (activator, repressor)
• Effectors (inducer, corepressor)
![Page 6: Regulation of gene expression in prokaryotes Katalin Kiss Dept. of Medical Biology 12.11. 2007.](https://reader034.fdocuments.net/reader034/viewer/2022051517/56649ed35503460f94be429d/html5/thumbnails/6.jpg)
Lactose operon (lac operon)
![Page 7: Regulation of gene expression in prokaryotes Katalin Kiss Dept. of Medical Biology 12.11. 2007.](https://reader034.fdocuments.net/reader034/viewer/2022051517/56649ed35503460f94be429d/html5/thumbnails/7.jpg)
RNA polymerase
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lactose
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CAP
![Page 10: Regulation of gene expression in prokaryotes Katalin Kiss Dept. of Medical Biology 12.11. 2007.](https://reader034.fdocuments.net/reader034/viewer/2022051517/56649ed35503460f94be429d/html5/thumbnails/10.jpg)
Regulatory elements of Lactose operon (Lac operon)
• Cis-acting elements: operator, promoter
• Regulatory proteins: Lac-repressor and CAP
• Effectors: lactose and cAMP = inducers
![Page 11: Regulation of gene expression in prokaryotes Katalin Kiss Dept. of Medical Biology 12.11. 2007.](https://reader034.fdocuments.net/reader034/viewer/2022051517/56649ed35503460f94be429d/html5/thumbnails/11.jpg)
Triptophan operon (Trp operon)
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Triptophan operon (Trp operon)
Alberts Fig. 7-34
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Attenuation of Triptophan operon (Trp operon)
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Regulatory elements of Tryptophan operon (Trp operon)
•Cis-acting elements: operator, promoter, attenuator
•Regulatory proteins: Trp-repressor
•Effectors: trp= korepresszor
![Page 15: Regulation of gene expression in prokaryotes Katalin Kiss Dept. of Medical Biology 12.11. 2007.](https://reader034.fdocuments.net/reader034/viewer/2022051517/56649ed35503460f94be429d/html5/thumbnails/15.jpg)
Animations of Lac operon and Trp operon on the web
• http://highered.mcgraw-hill.com/olc/dl/120080/bio27.swf
• http://www.dnatube.com/view_video.php?viewkey=712c49d51a18a32b39f0