BACTERIAL GROWTH Flashcards
1
Q
that change in cell number of cell mass per unit time
A
growth rate
2
Q
interval for the formation of two cells from one
A
generation
3
Q
the time required for the cell population to double
A
generation time/doubling time
4
Q
Exponential growth
A
peak of the growth of bacteria
5
Q
how long does Generation or doubling time take
A
20 min - 24 h
6
Q
phases of growth
A
bacterial growth curve
7
Q
describe lag phase
A
- bacteria first introduced in a media
- “checking out surroundings”
- cells are active metabolically
- no. cells changes very little
8
Q
lag phase takes how long
A
1 hr to several days
9
Q
describe log phase
A
- rapid cell growth
- population doubles every gen
- microbes are sensitive to adverse conditions
10
Q
formula for generation time (G)
A
G= t/n;
t=time
n=no. of generation
11
Q
describe stationary phase
A
- death rate=rate of reproduction
- cells encounter stresses
- endospores would form now
12
Q
describe death phase
A
- death rate > rate of reproduction
- due to limiting factors
13
Q
what are the physical requirements for growth
A
- temperature
- pH
- oxygen concentration
- moisture
- osmotic pressure
- radiation
14
Q
chemical/nutritional requirements fkr growth
A
- carbon
- nitrogen
- sulfur
- phosphorus
- trace elements
- vitamins
15
Q
effect on growth when there is minimum temp
A
membrane gelling; transport processes so slow that growth cannot occur
