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Control of Gene Expression Chapter 16 Genes and Development.

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Presentation on theme: "Control of Gene Expression Chapter 16 Genes and Development."— Presentation transcript:

1 Control of Gene Expression Chapter 16 Genes and Development

2 Proteins can determine the DNA sequence by binding the major groove of DNA. Proteins binding the minor groove cannot determine the exact sequence of bases.

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5 Prokaryotic gene regulation Lac Operon

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8 Prokaryotic gene regulation Trp Operon Biosynthesis of the amino acid typtophan Therefore, the regulation is the opposite of the lac operon.

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10 Eukaryotic gene regulation

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12 Enhancer (DNA sequence) Activator (protein) Looping

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16 1. Nucleosome sliding 2. Remodeled nucleosome 3. Nucleosome displacement4. Histone replacement ADP + ATP PiPi ATP -dependent remodeling factor

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18 Cytoplasm RNA Polymerase II microRNA gene Pri-microRNA Nucleus Drosha Exportin 5 Pre-microRNA Dicer Mature miRNA RISC mRNA RISC mRNA cleavage mRNA RISC Inhibition of translation RNA Polymerase II microRNA gene Pri-microRNA Nucleus Drosha Exportin 5 Pre-microRNA

19 Exogenous dsRNA, transposon, virus P P P P P P P P siRNAs + Ago RISC Ago RISC siRNA in RISC Cleavage of target mRNA Repeated cutting by dicer mRNA

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21 DNA 2. RNA splicing Gene expression can be controlled by altering the rate of splicing in eukaryotes. Alternative splicing can produce multiple mRNAs from one gene. Mature RNA transcipt Exons Introns 5´ cap 3´ poly-A tail Cut intron RNA polymerase II 3´3´ 5´5´ Primary RNA transcript 1. Initiation of transcription Most control of gene expression is achieved by regulating the frequency of transcription initiation.

22 3. Passage through the nuclear membrane Gene expression can be regulated by controlling access to or efficiency of transport channels. 4. Protein synthesis Many proteins take part in the translation process, and regulation of the availability of any of them alters the rate of gene expression by speeding or slowing protein synthesis. 3´3´ 5´5´ Small subunit Nuclear pore 5´ cap mRNA Large subunit 3´ poly-A tail

23 23 5. RNA interference Gene expression is regulated by small RNAs. Protein complexes containing siRNA and miRNA target specific mRNAs for destruction or inhibit their translation. 6. Posttranslational modification Phosphorylation or other chemical modifications can alter the activity of a protein after it is produced. Completed polypeptide chain RISC P P

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