Bacterial Growth

Question 1

What are 3 general mechanisms of toxin action?

Answer 1

1. Can form pores in cells
2. Traverse the membrane and damage the cell inside
3. Interact with signal proteins and cause downstream effects

Question 2

What is the Type III Secretory Apparatus?

Answer 2

Allows Gram (-) bacteria to inject virulence factors into the host

Question 3

What are the 4 phases of bacterial growth?

Answer 3

1. Lag phase- no growth
2. Exponential phase- consistent growth. This is usually the period of maximal growth, and the doubling time can be as fast as 20 minutes. This means, very roughly, that the population will increase eight-fold every hour.
3. Stationary phase- the net number of cells is approximately constant
4. Death phase- the number of cells decreases

Question 4

How do drugs attack DNA replication in bacteria?

Answer 4

Drugs can attack DNA gyrase which removes knots in the DNA, and this will target the bacterial version of the protein

Question 5

How do drugs target protein synthesis in bacteria?

Answer 5

The ribosome is the target of a very large group of antibiotics, including erythromycin, tetracycline’s, streptomycin and spectinomycin.

Question 6

What are the steps in the synthesis of the peptidoglycan?

Answer 6

a. The subunits of peptidoglycan are synthesized in the cytoplasm.
b. These subunits are transferred across the membrane by a carrier molecule.
c. The newly transferred subunits are cross linked to the peptidoglycan already present on the other side of the membrane

Question 7

What is the function of penicillin binding protein?

Answer 7

A group of proteins called penicillin-binding proteins serve to make and break these crosslinks during peptidoglycan maturation, an activity that is critical to cell growth.

Question 8

What are siderophores?

Answer 8

Siderophores are molecules secreted by bacteria that trap iron, and which can be transported back into the bacterium. Some siderophore genes are on plasmids and these plasmids are virulence factors.

Question 9

What is respiration in bacteria?

Answer 9

Respiration involves a highly efficient stepwise removal of energy (electron transport) that can be used to generate a gradient of protons across the bacterial membrane (oxidative phosphorylation)

Question 10

How is respiration targeted by drugs?

Answer 10

Any drug treatment that impairs the integrity of the cell envelope can destroy the gradient needed for respiration and kill the cell.

Question 11

What is an adaptive response to lack of nutrients?

Answer 11

The formation of spores by Bacilli and Clostridia are a response to a lack of nutrient by the formation of a dormant, resistant cell type. Spores can enhance or even be crucial for pathogenesis.

Question 12

What is an adaptive response to temperature?

Answer 12

Most bacteria can engage in a heat shock response, during which protective factors that allow the cells to survive increased heat and other stresses are synthesized.

Question 13

It is common to distinguish a variety of pathogens based on:
A. A diagnostic test of the ribosome structure.
B. The organic molecules produced during fermentation.
C. The particular cytochromes synthesized during respiration.
D. The attenuators that are used during pathogenesis.

Answer 13

D. The attenuators that are used during pathogenesis.

Question 14

In response to encountering its host, a pathogen is likely to:
A. To begin lag phase.
B. To synthesize and phosphorylate virulence plasmids.
C. To induce synthesis of a novobiocin-resistant DNA gyrase.
D. To engage in an adaptive response.

Answer 14

D. To engage in an adaptive response.

Things like production of pili/toxins