1. Bacterial Genetics

21. Direct Selection for Mutants

23. Indirect Selection: Isolation of ts Mutants This is one example of isolation of mutants carrying conditionally lethal mutations found in essential genes.

24. Indirect Selection: Replica Plating

25. Indirect Selection: Penicillin Enrichment

28. Self-Transmissible R Plasmid Resistance Transfer Factor (conjugation genes) Note multiple resistance genes.

37. Griffith’s Experiment

38. DNA as the Genetic Material The early work of Fred Griffith in 1928 on the transfer of virulence in the pathogen S. pneumoniae set the stage for DNA research.

39. Original Transformation Exp. F. Griffith (1928) using pneumococci

43. Transformation

48. Generalized Transduction

49. Specialized Transduction

52. Generalized Transduction Bacteriophages are viruses that only infect (and can kill) bacteria.

59. Conjugation: Sex or F Pilus

67. DNA-Mediated Transformation Note that DNA is taken up naked from the environment.

68. DNA-Mediated Transformation

69. Artificial Competence by Electroporation Competence denotes the ability to take up DNA naked from the environment. Most bacteria are not naturally competent but many can be made artificially so. Artificially induced competence is very important to gene cloning.

71. Restriction Endonuclease Action

72. Restriction Endonuclease Action Note in particular that DNA is cut at palindromic regions.

73. DNA Modification: RE Protection

76. Conjugation: F Plasmid Transfer

81. Generalized Transduction

84. Ames Salmonella Test