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Goals today:

Goals today:. Describe the parts of an operon Be able to compare an inducible and repressible operon. Prokaryotic Gene Regulation. The Major Players. Promoter – DNA found before the gene that signals where transcription should begin

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Goals today:

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  1. Goals today: Describe the parts of an operon Be able to compare an inducible and repressible operon

  2. Prokaryotic Gene Regulation

  3. The Major Players • Promoter – DNA found before the gene that signals where transcription should begin • Operator - DNA found before the gene that when bound to an active repressor prevents transcription • Structural Genes – the gene coding for enzymes • Regulator Gene – located outside of the gene, codes for repressor

  4. Operon • A term to describe all of these players!

  5. 2 famous operons1 = trpoperon Facts: • Regulator codes for protein that does not fit to operator • Means cell codes for AA tryptophan “by default” • If tryptophan is present – it binds to inactive repressor and activates it!

  6. Trpoperon • = repressible operon normally active because repressor is inactive • Tryptophan than we call a corepressor

  7. The Lac OperonAn inducible operon

  8. The Lac Operon • Keep in mind  most prokaryotes will prefer glucose as an energy source • When it is not present prokaryotes will look to other sources

  9. Lac Structural Genes • Genes that code for enzymes that aid in digestion of lactose! • How are these different than Trpoperon?

  10. Lacoperon • Repressor gene codes for an active repressor • Remember active repressor binds to operator  no transcription • Lactose can bind to this repressor and DEACTIVATE IT • Lactose bound to repressor means transcription can be promoted!

  11. Meet cAMP • What is ATP broken down into? • Having an AMP around likely means what? • No Gluclose means less ATP

  12. cAMP le gusta CAP • CAP = catabolite activator protein • cAMP binds with CAP • This complex attaches to CAP binding site next tolacpromoter • Bends DNA so promoter easier for RNA polymerase to find

  13. Lets sum it up • What does cAMP tell the cell? • What does an inactive repressor tell the cell

  14. The rest of class • Discuss this stuff… • In writing Personify these two operons! • Share with your classmates

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