1. Genetics of Bacteria
Chapter 8 Part 2

2. Acquisition of additional DNA  ♀♂

3. Transformation is 2nd of the three ways bacteria acquire DNA1 3

4. Transformation in Bacteria
First need competent bacteria
with receptor sites
Swap!

5. Naturally Competent Bacteria
About 1% of bacterial species capable of taking up DNA under lab conditions.
These species have genes that protein machinery to bring DNA across
membrane.
Artificial Competence:
45 C Heat-shock and high calcium can induce transformation

6. Transformation in Bacteria
First need competent bacteria
with receptor sites
Swap!

7. 2 1 3 Transduction is 3rd of the three ways bacteria acquire DNA
Transduction is Virus-Mediated Bacterial DNA Transfer 2 1 3

8. Phages
Protein

9. Phages Attacking Bacteria

10. Phages Bacterial Transcription and Translation machinery
is used by Viral DNA

11. Plaque Assay – How To Measure Response
Concentrated
Phages
Super Dilute

12. 3 – Transduction – two different autotrophic strains

13. Lederberg-Zinder experiment
P-22 Phages
Do no disrupt
LA-22 bacteria

14. Lederberg-Zinder experiment
P-22 Phages
small enough
to pass thru
Filter, infect
LA-2 and
Incorporate
LA-2 DNA

15. Lederberg-Zinder experiment
P-22 Phages
incorporate
LA-2 DNA
then cross
back and
pass DNA to
LA-22

16. Transduction (Virus-Mediated Bacterial DNA Transfer)
tells us about gene proximity due to small fragments
moved by the viruses.

17. Quorum sensing bacteria

18. quorum sensing – a molecular communication system
Bacterial cells use quorum sensing to count themselves, determine
when they have reached an optimal density, and adjust their
behavior synchronously
For example, when virulent bacteria invade a host organism,
they wait until their numbers exceed a critical mass
before secreting toxins.
Timing is key.
If bacteria release these toxins too soon, they risk getting
wiped out by the host immune system.

19. quorum sensing – a molecular communication system
Bacterial cells use quorum sensing to count themselves, determine
when they have reached an optimal density, and adjust their
behavior synchronously
Signaling molecules