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Announcements

Announcements. You must go and check your plates today! Ch. 8 Part 1 homework is due Monday Remember how to submit it if you miss class Friend Scan and email it Put in box…Just make sure it is BEFORE class ends (if it’s not in there by 10 AM then a “0”). Bacterial Genetics Chapter 8 Part 1.

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Announcements

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  1. Announcements • You must go and check your plates today! • Ch. 8 Part 1 homework is due Monday • Remember how to submit it if you miss class • Friend • Scan and email it • Put in box…Just make sure it is BEFORE class ends (if it’s not in there by 10 AM then a “0”)

  2. Bacterial GeneticsChapter 8 Part 1

  3. Think-Pair-Share Question (2 Mins) Bacteria use 2 methods to change their gene expression, what are they? Hint: 1 you know in detail Answer: 1. Regulating Gene Expression deliberate, intentional! (Ch.7) 2. Genetic Change via mutations (this is random!) or acquiring DNA from another bacteria (horizontal gene transfer)

  4. Think-Pair-Share Question (2 Mins) Which statement is correct? • Natural selection and evolution drive mutations. • Random mutations that lead to better survival/reproduction are acted on by natural selection. MISCONCEPTION!!

  5. Based On The Correct Understanding Of Natural Selection… For a bacterium, did the genetic change happen first that became an advantage for survival -or- does the need for better survival drive the formation of genetic change?

  6. The Point: Change Then Natural Selection Based on Environment Not the Other Way Around! • Mutations and acquiring DNA is random • If it leads to better survival and there is a need for that variant (because of some factor) then those will be selected for (passed on)! Environmental Change Random Mutation Pass the mutation on! Natural Selection

  7. Let’s Review • Genotype: the set of genes an organism carries • Again, the name gives it away: geno=gene • Phenotypes: organism’s appearance Phenotype ahpC lacZ lacA Genotype

  8. Two Ways To Get Mutations • Spontaneously • Result from normal processes • 3 types • Rate that this occurs for a gene is 1 in 10,000 to 1 in a trillion • Can a mutation go back to the original form? rare, but it does happen: reversion • Question: Are 2 mutations likely? Incredibly Rare Event! • How do you know? • Induced • Occur by external forces: chemicals, radiation

  9. Spontaneous Mutations: Base Substitution • If one base is changed-point mutation

  10. Spontaneous Mutations: Base Substitution Outcomes

  11. Spontaneous Mutations: Deletion or Addition of Bases • Causes a frameshift mutation

  12. Spontaneous Mutations: Transposons

  13. Induced Mutations: Chemicals (Alkylating Agents)

  14. Induced Mutations: Chemicals (Base Analogs)

  15. Induced Mutations: Chemicals (Intercalating Agents) • Cause a frameshift mutation • Used in lab settings to stain DNA

  16. Induced Mutations: Chemicals (UV Light) • Distorts DNA • Cell dies if damage cannot be repaired

  17. How do cells repair the damage caused spontaneously and or induced by chemicals or radiation?

  18. Spontaneous Mutation Repair: Mismatch Repair

  19. Induced Mutations: UV Light Repair

  20. Induced Mutations: UV Light Repair Cont. • SOS Repair-Last ditch effort to repair DNA • Do you know what SOS stands for? • Normal DNA polymerase stalls when it gets to areas of extensive damage • But if the SOS system has been activated, a special DNA polymerase can replicate DNA even if it is highly damaged

  21. Why are correcting mutations important? • For microbes, mutations that lead to alterations in DNA replication, protein expression and function can result in death • For humans and animals, if you don’t correct mutations you can get cancer

  22. Let’s Work a Problem Together…

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