Bacterial Genetics

Question 1

What can regulate bacterial gene expression?

Answer 1

1. Temperature
2. pH
3. Changes in carbon and nitrogen availability (sugars and amino acids)
4. Osmolarity
5. Oxygen and other electron acceptors
6. Carbon Dioxide
7. Bacterial cell density (quorum sensing)
8. contact with Host cells
9. Iron availability, divalent cations (Ca++, Mg++, Mn++)

Question 2

What is a good example of regulation of toxin expression?

Answer 2

Diptheria

Question 3

Can bacterial transcription and translation occur at the same time?

Answer 3

Yes

Question 4

What are sigma factors and what do they do?

Answer 4

Proteins that recognize specific promoter sequences and direct the RNA Polymerase complex where to bind within DNA

Question 5

How do bacteria change their genetic makeup?

Answer 5

• Mutation

- Horizonatl gene exchange mechanisms

Question 6

What are some mechanisms of genetic change and diversification in bacteria?

Answer 6

1. Point Mutation
   
   • Nucleotide change, insertion, or deletion
2. Gene duplication
3. Gene deletion
4. Chromosomal rearrangement
   
   • Inversion
   • Intragenic recombination

Question 7

What is the mutation rate of bacteria?

Answer 7

10E-6 to 10E-9 per nucleotide per bacterial generation under normal culture conditions

Question 8

What effects can gene amplification and duplication have?

Answer 8

Resistance to sulphonamide, trimethoprim, and Beta-Lactams can be conferred by increased gene dosage through duplication/amplification of antibiotic hydrolytic enzymes, target enzymes, or efflux pumps

Question 9

What are the 3 main methods of horizontal gene transfer?

Answer 9

1. Bacterial Transformation
2. Bacterial Transduction
3. Bacterial Conjugation

Question 10

What effects can Point mutation have?

Answer 10

can impact gene expression of virulence factors (e.g. premature truncation of toxins) and the sensitivity of antibiotic targets (e.g. rifampicin). The latter usually comes with a fitness cost