1. Bacterial and Viral Genetic Systems Part I Ch. 8 Ebola virus Cholera bacteria H. pylori

2. Outline Techniques to study bacteria The bacterial genome Plasmids Gene Transfer Mapping bacterial genes Antibiotic resistance Bacterial transformation

3. Bacterial “in vitro” growth Liquid OR solid agar plates You will do in lab next week

4. Bacterial Growth Minimal Growth Media Complete Growth Media For prototrophs For auxtrophs (mutants) Bacterial Colony Colonies are “clones”

5. Mutant bacteria: can be found based on their “food” requirements

6. Bacterial Genome (normally—there are exceptions) A circular chromosome Haploid Normally compact DNA NO nuclear membrane: prokaryote—no exception to this rule DNA “escaping” out of damaged cell

7. Bacterial Plasmids 1.What are they? 2.What affect can they have on the bacterial cell? 3.How did they get inside the cell? 2 plasmids joined together Some plasmids are integrated And some remain independent. Episomes can be either!

8. Episome The fertility factor (F factor) is an episome Controls gene exchange and mating in bacteria

9. Methods for bacterial gene transfer (in nature) Conjugation Transformation Transduction You will do this in the lab!

10. Methods for bacterial gene transfer (in nature) Conjugation: bacteria to bacteria Transformation: external environment to bug (bacteria) Transduction: from virus to bug! DNA transfer is not linked to reproduction in bacteria.

11. Methods for bacterial gene transfer (in nature) Conjugation: often involves recombination Transformation: May have recombination Transduction: May have recombination How do we know?

12. Experimental evidence to support bacterial recombination MINIMAL MEDIA NO GROWTH ON EITHER PLATE MIX STRAINS SOME GROWTH

14. Most conjugation transfers requires the “F” factor Sex pilus

16. Bacterial Recombination Certain bacterial cells show recombination with “F” factor These are called High-frequency (Hfr) cells

18. Hfr cells and stepwise recombination

19. Hfr cell to a F’ cell The F factor is cut from the bacterial chromosme and may even carry some bacterial chromosome with it!

20. Partial diploids F’ can conjugate with F- cell. Leads to “partial diploid”= merozygotes Two copies of some genes

21. Mapping bacterial genes Using “interrupted conjugation

23. Transfer times indicate map distances 0 5 10 1520 origin azi ton lacgal 25

24. R Plasmids Contain genes for antibiotic resistance Easily spread among unrelated bacteria Fish bacteria E. coli

25. Transformation Uptake of DNA by bacteria from its external environment May be DNA fragment Bacterial cell must be “competent” May recombine with host’s DNA TRANSFORMANTS

26. Transformation can be also used to map bacterial genes

27. Note: You will carry out a bacterial transformation in lab next week; however, there will be some technical differences from what may occur in nature. I will emphasize these in lab. Next we complete chapter 8 –Viral genetic systems