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Bacterial Genetics.

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Presentation on theme: "Bacterial Genetics."— Presentation transcript:

1 Bacterial Genetics

2 Bacteria Have Circular Chromosomes
Cell Wall Cytoplasm Cell Membrane Chromosome Origin of Replication Termination of Replication

3 Replication Replication goes in both directions Original Chromosome
Start of replication Theta (q) structure End of replication Two chromosomes Mid replication

4 Binary Fission

5 Ways Bacteria Exchange Genetic Material
Transformation - Bacteria take up DNA from their environment and incorporate it into their genome (i.e. the Griffith experiment) Conjugation - The direct transfer of DNA by bacteria usually via plasmids Transduction - Movement of DNA between bacteria by viruses

6 1 Transformation Crossing over Insertion

7 1 Transformation

8 1 Transformation

9 1 Transformation

10 1 Transformation

11 1 Transformation

12 Crossover Frequency Following binary fission, one daughter cell will have the recombinant strand and thus have a recombinant chromosome Mapping bacterial genes following transformation is not significantly different from eykaryotic mapping. The closer two genes are to one another, the lower the probability of a crossover event between them and thus the higher the probability that they will be co-transformed A B C Transformation with A and C is unlikely A B C

13 2 Conjugation F plasmid F plasmid F+ bacteria F- bacteria
Mating Bridge F- bacteria F plasmid

14 2 Conjugation F plasmid F plasmid F+ bacteria F- bacteria
Mating Bridge F plasmid

15 2 Conjugation F plasmid F plasmid F+ bacteria F- bacteria
Mating Bridge F plasmid

16 2 Conjugation F plasmid F plasmid F+ bacteria F- bacteria
Mating Bridge F plasmid

17 2 Conjugation F plasmid F plasmid F plasmid F+ bacteria F- bacteria
Mating Bridge F plasmid F plasmid

18 Transfer of genetic material
Hfr Recombination F+ bacteria F plasmid Integration Hfr cell Transfer of genetic material F- bacteria

19 Transfer of genetic material
Hfr Recombination F+ bacteria F plasmid Integration Hfr cell Interruption of conjugation F- bacteria Crossing over Transfer of genetic material

20 Hfr Recombination F+ bacteria F plasmid Integration Hfr cell
Recombinant Bacteria

21 3 Transduction Generalized
Destruction of the bacteria’s DNA Infection Replication of the viral genome Production of viral parts Packaging Lysis

22 3 Transduction Specialized
Temperate Phage Part of the bacteria’s DNA Replication of the viral genome Production of viral parts Packaging Lysis


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