Bacteria Genetics

2. Bacteria Genetics

3. Introduction • Chromosome (bacteria are haploid; in other words, they have a single chromosome) • Mutations (change in the base sequence of DNA) • Extrachromosomal genetic material Plasmid Transposons • Genetic recombination : Transfer of DNA from one bacterium to another

4. Introduction • Changes in the genome can occur by two processes • Mutations • Genetic recombination • The changes in the genome is of considerable importance in terms of bacterial virulence and drug resistance

5. Genetic Recombination The transfer of DNA from one organism to another with subsequent integration into the DNA of the recipient

6. Genetic Recombination • Three mechanisms • Transformation • Transduction • Conjugation

7. Transformation Definition • Genetic recombination in which a DNA fragment from a dead degraded bacterium enter a competent recipient bacterium and is exchanged for a piece of DNA of the recipient Mechanism • Dead/donor bacterium – source of DNA • DNA fragment from the dead donor bacterium binds to DNA binding protein on the cell wall of the competent living recipient bacterium

8. Transformation

9. Transduction Definitions • Transduction - Genetic recombination in which a DNA fragment is transferred from one bacterium to another by a bacteriophage • Bacteriophage - A virus that only infects bacteria horiz gene transfer-, Transposons--robert

10. Transduction

11. Conjugation • Genetic recombination in which there is a transfer of DNA from a living donor bacterium to a recipient bacterium, often thorugh a sex pilus. • Pilus - A tubular protein structure extending from a bacterial surface used for attachment to environmental surfaces or cells. A sex pilus is involved in bacterial conjugation.

12. Plasmid Conjugation

14. R Plasmid Conjugation