1. 1 Genetic Information in Bacterial Cells

2. 2 Bacterial Reproduction: Binary Fission Bacterial chromosome and Plasmids to each

3. 3 Types of Gene Transfer in Bacterial Cells Transformation - ‘naked’ DNA fragments from donor to recipient Transduction - Virus carries DNA fragment from donor to recipient Conjugation - Cell : Cell contact required Donor cell: F +, Hfr Recipient: F -

4. 4 Gene Transfer in Bacteria Linear or circular DNA is transferred

5. 5 Transformation DNA from disrupted donor Homologous Recombination Double CO Heteroduplex DNA replication Closely linked genes cointegrate Transformant with new phenotype

6. 6 Transformation: Determining Gene Order Would you see p + q o + transformants?

7. 7 Transformation: Determining Gene Order Sample problem Least frequent, so a-b far apart a-c closer together b-c closer together Therefore a - c - b

8. 8 Transduction: Life Cycle of Phage Lytic or Lysogenic

9. 9 Transduction: Generalized Fragments of bacterial chromosome randomly packaged into phage

10. 10 Transduction: Generalized Integration requires DCO Cotransduction indicates linkage

11. 11 Transduction: Specialized Phage integrates Takes specific gene with it during excision

12. 12 Conjugation Lederberg & Tatum (1946) Davis (1946) Cell contact required

13. 13 Conjugation Sex pilus (F-pilus)F + cells F factor - plasmid

14. 14 Conjugation: F + x F - mating F factor nicked at origin Rolling circle replication Linear transfer of genes 5 4 3 2 1 F Recipient becomes F +

15. 15 Conjugation: Origin of Hfr cells F factor integrates a b c m p p m c b a

16. 16 Conjugation: Hfr x F - cells New genes must integrate into bacterial chromosome Trans-conjugant still F -

17. 17 Conjugation: Transfer of Genes from Hfr Cell Genes transferred in order Minute mapping possible

18. 18 Conjugation: Transfer of Genes from Hfr Cell Minute Mapping

19. 19 Conjugation: Interrupted-Mating with Hfr Strains Determine gene order, position and orientation of F factors

20. 20 Conjugation: Sample Problem Hfr Mapping Indicate positon of each gene, each F-factor, and orientation

21. 21 Conjugation: Determining Gene Order Also applicable to Transformation and Transduction

22. 22 Conjugation: Determining Gene Order

23. 23 Conjugation: Determining Gene Order Order is d-f-e or e-f-d

24. 24 Conjugation: Origin of F’ Strains F’ cell Transfers specific genes Recipient - merozygote partial diploid

25. 25 Genetic Analysis of Viruses Viruses - small genome, rapid reproduction large numbers enable mapping within genes (1 in 10 12 recombinants observed)

26. 26 Benzer’s Experiments: T4 bacteriophage Wild type Rapid lysis (rII) mutants Small rough plaquesLarge round plaques Grow in E. coli Strains B and K12 Strain B, NOT K12

27. 27 Benzer’s Experiments: T4 bacteriophage Complementation tests with numerous rII mutants K12

28. 28 Benzer’s Experiments: T4 bacteriophage Intragenic mapping of independently isolated rII A mutants Transfer to strain K12 to select for wild-type recombinants Frequency = distance between different mutation E.coli B

29. 29 Deletion Mapping Facilitates mapping of mutations If mutation is in region of deletion, no wild-type recombinants occur. If mutation is in different region, wild-type recombinants will occur.

30. 30 Deletion Mapping: Sample Problem 1 Locations of deletions (white) and DNA ( ) Where is a3 located?

31. 31 Deletion Mapping: Sample Problem 2 Line represents deletion, intact DNA is not shown Where is a3 located?

32. 32 Deletion Mapping: Complete map of rII locus Locations of