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Chapter 18 Genetics of Viruses and Bacteria

Chapter 18 Genetics of Viruses and Bacteria. Gene Regulation. Gene Regulation. Your body needs to make tryptophan. Gene Regulation. There are 5 steps to making tryptophan. Gene Regulation. Eventually you have enough tryptophan. Gene Regulation.

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Chapter 18 Genetics of Viruses and Bacteria

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  1. Chapter 18Genetics of Viruses and Bacteria Gene Regulation

  2. Gene Regulation Your body needs to make tryptophan.

  3. Gene Regulation There are 5 steps to making tryptophan.

  4. Gene Regulation Eventually you have enough tryptophan.

  5. Gene Regulation High levels of tryptophan inhibits the first enzyme in the process that makes more tryptophan.

  6. Gene Regulation This is negative feedback.

  7. Gene Regulation This is negative feedback. Making tryptophan

  8. Gene Regulation This is negative feedback. means Making tryptophan we have more

  9. Gene Regulation This is negative feedback. which inhibits means Making tryptophan we have more

  10. Gene Regulation This is negative feedback. which inhibits means Making tryptophan we have more

  11. Gene Regulation Negative feedback is also used to regulate the genes that make the five enzymes that make tryptophan. A B C D E

  12. Gene Regulation DNA codes for these enzymes. ======================EDCBA=====

  13. Gene Regulation RNApolymerase has to attach to the DNA to start transcription of the genes. ======================EDCBA=====

  14. Gene Regulation It needs a place to attach. The promoter is a region of DNA that marks the beginning of the gene. ======================EDCBA=====

  15. Gene Regulation It needs a place to attach. The promoter is a region of DNA that marks the beginning of the gene. ======================EDCBA=====

  16. Gene Regulation It needs a place to attach. The promoter is a region of DNA that marks the beginning of the gene. ======================EDCBA=====

  17. Gene Regulation RNA polymerase makes the mRNA for the five enzymes. ======================EDCBA===== EDCBA

  18. Gene Regulation The mRNA goes to the ribosomes where the five enzymes are made. ======================EDCBA===== ABCDE

  19. Gene Regulation The five enzymes make tryptophan. ======================EDCBA=====

  20. Gene Regulation When there is enough tryptophan, the first enzyme is inhibited. ======================EDCBA=====

  21. Gene Regulation But the genes could still go on making more enzymes. ======================EDCBA=====

  22. Gene Regulation But the genes could still go on making more enzymes. ======================EDCBA===== ABCDE

  23. Gene Regulation But the genes could still go on making more enzymes. ======================EDCBA===== ABCDE

  24. Gene Regulation But the genes could still go on making more enzymes. ======================EDCBA=====

  25. Gene Regulation But the genes could still go on making more enzymes. ======================EDCBA===== ABCDE

  26. Gene Regulation But the genes could still go on making more enzymes. ======================EDCBA===== ABCDE

  27. Gene Regulation You really don’t need all those enzymes if you’re not using them. ======================EDCBA=====

  28. Gene Regulation You want to be able to shut off the gene. Actually, you want to shut off all 5 genes. ======================EDCBA=====

  29. Gene Regulation The repressor gene trpR makes a repressor molecule. ==trpR================EDCBA=====

  30. Gene Regulation The repressor gene trpR makes a repressor molecule. ==trpR================EDCBA=====

  31. Gene Regulation The repressor gene trpR makes a repressor molecule. ==trpR================EDCBA=====

  32. Gene Regulation The repressor gene trpR makes a repressor molecule. ==trpR================EDCBA===== trpR

  33. Gene Regulation The repressor gene trpR makes a repressor molecule. ==trpR================EDCBA===== trpR

  34. Gene Regulation The repressor gene trpR makes a repressor molecule. ==trpR================EDCBA===== trpR

  35. Gene Regulation The repressor is inactive. ==trpR================EDCBA=====

  36. Gene Regulation It needs tryptophan to be a corepressor in order to activate it. ==trpR================EDCBA=====

  37. Gene Regulation When there is a lot of tryptophan, enough repressor is activated to shut down the gene. ==trpR================EDCBA=====

  38. Gene Regulation The activated repressor binds to the operator region inside the promoter. ==trpR================EDCBA=====

  39. Gene Regulation This prevents RNA polymerase from binding to DNA. ==trpR================EDCBA=====

  40. Gene Regulation This prevents RNA polymerase from binding to DNA. ==trpR================EDCBA=====

  41. Gene Regulation This prevents RNA polymerase from binding to DNA. ==trpR================EDCBA=====

  42. Gene Regulation The operon includes the promoter, operator, and all five genes. ==trpR================EDCBA=====

  43. Gene Regulation The regulatory geneis separate. ==trpR================EDCBA=====

  44. Gene Regulation The repressor is inactive ==trpR================EDCBA=====

  45. Gene Regulation The repressor is inactive until the corepressor binds to it. ==trpR================EDCBA=====

  46. Gene Regulation The genes that make tryptophan are repressible genes. ==trpR================EDCBA=====

  47. Positive Feedback

  48. Positive Feedback E. coli needs three separate enzymes to digest lactose.

  49. Positive Feedback Tryptophan was something the cell needed to make, so the trp gene was repressed by tryptophan.

  50. Positive Feedback Lactose is something the cell needs to digest, so the lac gene is induced by lactose.

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