1. Bacterial Genetics

2. Bacterial Genome  Chromosome:  Plasmid: Plasmids are extrachromosomal genetic elements capable of autonomous replication. An episome is a plasmid that can integrate into the bacterial chromosome.  IS or Tn

4. Mechanism of bacterial variation  Gene mutation  Gene transfer and recombination  Transformation  Conjugation  Transduction  Lysogenic conversion  Protoplast fusion

5. Types of mutation  Base substitution  Frame shefit  Insertion sequences

6. What can cause mutation?  Chemicals: nitrous acid; alkylating agents 5-bromouracil benzpyrene  Radiation: X-rays and Ultraviolet light  Viruses

7. Bacterial mutation  Mutation rate  Mutation and selectivity  Backward mutation

8. Transformation  Transformation is gene transfer resulting from the uptake by a recipient cell of naked DNA from a donor cell. Certain bacteria (e.g. Bacillus, Haemophilus, Neisseria, Pneumococcus) can take up DNA from the environment and the DNA that is taken up can be incorporated into the recipient's chromosome.

14. Conjugation  Transfer of DNA from a donor to a recipient by direct physical contact between the cells. In bacteria there are two mating types a donor (male) and a recipient (female) and the direction of transfer of genetic material is one way; DNA is transferred from a donor to a recipient.

15. Physiological States of F Factor  Autonomous (F + ) Characteristics of F + x F - crosses  F - becomes F + while F + remains F +  Low transfer of donor chromosomal genes F+

16. Physiological States of F Factor  Integrated (Hfr) Characteristics of Hfr x F - crosses  F - rarely becomes Hfr while Hfr remains Hfr  High transfer of certain donor chromosomal genes F+F+ Hfr

17. Physiological States of F Factor  Autonomous with donor genes (F’) Characteristics of F’ x F - crosses  F - becomes F’ while F’ remains F’  High transfer of donor genes on F’ and low transfer of other donor chromosomal genes Hfr F’

18. Mechanism of F + x F - Crosses  DNA transfer Origin of transfer Rolling circle replication Pair formation – Conjugation bridge F+F+ F-F- F+F+ F-F- F+F+ F+F+ F+F+ F+F+

19. Mechanism of Hfr x F - Crosses  DNA transfer Origin of transfer Rolling circle replication  Homologous recombination Pair formation – Conjugation bridge HfrF-F- F-F- F-F- F-F-

20. Mechanism of F’ x F - Crosses  DNA transfer Origin of transfer Rolling circle replication Pair formation – Conjugation bridge F’ F-F- F-F-

21. R Plasmid

22. Transduction:  Transduction is defined as the transfer of genetic information between cells through the mediation of a virus (phage) particle. It therefore does not require cell to cell contact and is DNase resistant.

23. Generalized Transduction  Generalized transduction is transduction in which potentially any bacterial gene from the donor can be transferred to the recipient.

24. The mechanism of generalized transduction

28. Generalized transduction 1. It is relatively easy. 2. It is rather efficient (10 -3 per recipient with P22HT, 10 -6 with P22 or P1), using the correct phage. 3. It moves only a small part of the chromosome which allows you to change part of a strain's genotype without affecting the rest of the chromosome. 4. The high frequency of transfer and the small region transferred allows fine-structure mapping

29. Specialized transduction  Specialized transduction is transduction in which only certain donor genes can be transferred to the recipient.  Different phages may transfer different genes but an individual phage can only transfer certain genes  Specialized transduction is mediated by lysogenic or temperate phage and the genes that get transferred will depend on where the prophage has inserted in the chromosome.

30. The mechanism of specialized transduction

31. Specialized transduction 1. Very efficient transfer of a small region--can be useful for fine-structure mapping 2. Excellent source of DNA for the chromosomal region carried by the phage, since every phage carries the same DNA. 3. Can often be used to select for deletions of some of the chromosomal genes carried on the phage. 4. Merodiploids generated using specialized phage can be quite useful in complementation analyses.

32. Lysogenic conversion  The prophage DNA as a gene recombined with chromosome of host cell.

33. Protoplast Fusion  Fusion of two protoplasts treated with lysozyme and penicillin.

34. Application of bacterial variation  Use in medical clinic: Diagnosis, Treatment, Prophylaxis.  Use in Genetic Engineering