Bacterial Genetics

Question 1

Vertical gene transfer ?

Answer 1

1. Donor to recipient thats not offspring
2. Transformation
3. Conjugation
4. Transduction

Question 2

What is transformation ?

Answer 2

DNA fragment from degraded bacteria -> enters environment -> taken up by competent bacteria

S. Pneumonia
Hib
Neiserria

Adding deoxyribonuclease degrades DNA and blocks transformation

Question 3

What is conjugation ?

Answer 3

DNA fragment from live bacteria transferred to recipient via
“Cell to cell contact”
- needs sex pilus

Question 4

What is F+ plasmid ?

Answer 4

Contains genes required for sex pilus and conjugation.

Mechanism of antibiotic resistance

Question 5

F+ x F- conjugation

Answer 5

Sex pilus on F+ contacts F-
ssDNA plasmid transferred across bridge

No transfer of chromosomal DNA

Question 6

Hfr x F- conjugation

Answer 6

F+ becomes part of chromosomal DNA (Hfr)

Integrated plasmid in chromosome transferred

Usually partial transfer

Recipient remains F- but now has new bacterial genes

Question 7

Hfr bacterium

Answer 7

Bacteria with F+ plasmid incorporated in DNA chromosome

Question 8

What is transduction ?

Answer 8

Transfer of dna from bacteria via bacteriophage

Question 9

Generalised transduction ?

Answer 9

Bacteriophage infects donor -> carries donor dna by mistake-> infects recipient

Eg. Penicillinase plasmid