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Control of Gene Expression

Control of Gene Expression. Chapter 16 Genes and Development. 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. Prokaryotic gene regulation Lac Operon. Prokaryotic gene regulation

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Control of Gene Expression

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  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.

  3. Prokaryotic gene regulation Lac Operon

  4. Prokaryotic gene regulation TrpOperon Biosynthesis of the amino acid typtophan Therefore, the regulation is the opposite of the lacoperon.

  5. Eukaryotic gene regulation

  6. Enhancer (DNA sequence) Looping Activator (protein)

  7. Pi ADP + ATP ATP -dependent remodeling factor 2. Remodeled nucleosome 1. Nucleosome sliding 3. Nucleosome displacement 4. Histone replacement

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

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

  10. RNA polymerase II 1. Initiation of transcription Most control of gene expression is achieved by regulating the frequency of transcription initiation. 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. Cut intron DNA 3´ 3´ poly-A tail 5´ cap Exons 5´ Mature RNA transcipt Primary RNA transcript Introns

  11. Large subunit 3. Passage through the nuclear membrane Gene expression can be regulated by controlling access to or efficiency of transport channels. 3´ poly-A tail Nuclear pore mRNA 5´ cap Small subunit 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´ 5´

  12. Completed polypeptide chain 6. Posttranslational modification Phosphorylation or other chemical modifications can alter the activity of a protein after it is produced. 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. P RISC P

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