Environmental stress response Flashcards
1
Q
What causes stress?
A
- starvation
- acidity
- hyperosmolarity
- high or low temp
2
Q
What is osmotic balance?
A
- mechanosensitive channels protect cell from sudden decreases in external osmotic pressure
3
Q
when do channels open for osmotic balance?
A
- under conditions of hypoosmotic stress and allow internal solutes to rapidly exit
4
Q
What is a batch culture?
A
- finite amount of nutrients
- each cell has own life cycle
5
Q
What is a lag phase?
A
- adjustment to new media with no growth
6
Q
What happens during exponential growth?
A
- nutrients run out, vulnerable as all energy goes toward growth
7
Q
What is the stationary phase?
A
- more focused on survival (more tolerant)
- growth = death
8
Q
What is the death phase?
A
- death>growth
- some feed off of dead neighbors and get little blips of nutrients
9
Q
Cells entering stationary phase more ______ to environmental stress
A
resistant
10
Q
what are toxic oxygen products?
A
- hydroxyl radical
- superoxide radical
- hydrogen persoxide
11
Q
What enzyme is required to dissociate toxic oxygen products?
A
- superoxide dismutase or catalase
12
Q
What happens during heat-shock?
A
- heat-shock proteins (Hsps) synthesis increases relative to synthesis of other proteins
13
Q
Hsps play important roles in ____ at all temp
A
growth
14
Q
What do hsps function as?
A
- repair/eliminate proteins that are damaged by heat stress
15
Q
What is RpoH responsible?
A
- heat-shock protein synthesis; mutants deficient in RpoH cannot grow above 20 degrees C
