Ch. 2 (2.2 and 2.6 only) Flashcards
1
Q
What does growth physiology include?
A
- Regulation of macromolecular synthesis, DNA division, etc.
- Adaptive responses to external environment
2
Q
What is a growth curve?
A
Observation of the sequence of growth phases following inoculation into fresh media
3
Q
What are the 4 phases in a growth curve?
A
- Lag phase
- Log phase/exponential growth
- Stationary phase
- Death phase
4
Q
Draw a general growth curve.
A
5
Q
What happens during the lag phase?
A
- Time required for physiological adaptation of stationary phase cells
- Preparing for growth
6
Q
Why does the lag phase occur?
A
- Recovering from toxic waste products that have accumulated in media
- New enzymes/co-enzymes must be synthesized before growth
- Dead cells in inoculum may contribute to turbidity but not growth
7
Q
What happens during the log phase/exponential growth?
A
Cell divide
8
Q
What happens during the stationary phase?
A
Cells stop growing
9
Q
Why does the stationary phase occur?
A
- Exhaustion of nutrients
- Limitation of oxygen
- Accumulation of toxic products
10
Q
What happens during the death phase?
A
Cells start dying
11
Q
Why does the death phase occur?
A
- Depletion of cellular energy
- Activity of autolytic enzymes
12
Q
How do bacteria adapt to starvation conditions (2 general methods)?
A
- Some sporulate or form desiccation resistant cysts
- Others undergo adaptive changes and enter the stationary phase
13
Q
What changes do bacteria undergo during starvation?
A
- Smaller cell size
- Change from rod to coccoid shape
- May become more adhesive
- Membrane phospholipids get converted to cyclopropyl derivatives
- Metabolic activity slows down
- New proteins with specific functions related to the decreased component
14
Q
Under what conditions is sigma S activated?
A
- Starvation conditions
- Changes to resistance to environmental stress
15
Q
Sigma S is also known as _____ or _____?
A
- rpoS
- σ38
