1. 1. How does conjugation work? Sex in Bacteria How do bacteria exchange DNA

2. Fig. 14.9

3. Fig. 14.11

5. What question did Tatum and Lederberg set out to answer? What led them to expect bacteria exchanged genetic information? Why did he pick the bacteria (E. coli) he used as starting material?

7. Why did Lederberg want to use multiple mutations? How did he get multiple mutations? What kind of mutations are made by X-rays And what kind by UV light?

8. What did Lederberg do to get recombinants?

9. How did Lederberg rule out possible explanations for his data that did not involve exchange of genetic information between strains? eg. Cross feeding (syntropism) Transformation

11. After conjugation what are the most common products? What do the rare classes represent? Did recombination occur in both directions?

12. Fig. 14.11 Davis U tube experiment 1950 Tatum and Lederberg 1947

13. Fig. 14.12a

14. Fig. 14.12b

15. Fig. 14.13

16. Fig. 14.14

17. Fig. 14.15

18. Fig. 14.16

19. Fig. 14.17

20. Is this recombination mechanism equivalent to sexual recombination in eukaryotes?

21. Three E. coli genomes: K12, UPEC 536 and UPEC CFT073. Blue: core genome Red: 2 pathogens only Green: 536 only Orange: in both pathogens but in different locations From Brzuszkiewicz et al 2006 PNAS 103, 12879. Bacterial genomes differ in gene content even within one species

22. Whole genome comparisons of bacterial genomes reveal differences in phage content and DNA islands

23. Plant pathogens differ in content and location of virulence genes. Horizontal transfer is source of Variation for virulence factors Compare location of type III effectors In two genomes of Pseudomonas syringae. tomato bean From Chang et al 2005 PNAS 102, 2549.

24. DNA exchange in bacteria leads to development of new niches, Adaptation to new hosts, Escape from host defense mechanisms