Microbial Population Growth

Question 1

equation for the mean growth rate (k) of your organism/ culture?

Answer 1

[log(Nt)-log(No)]/ (0.301)(t)

Question 2

equation for mean generation (doubling) time?

Answer 2

g=1/k

Question 3

phases of batch culture growth

Answer 3

-lag phase
-exponential phase
-stationary phase
-death phase

Question 4

Describe the lag phase

Answer 4

-variable in time
-stops when accumulated
-fastest phase

Question 5

Describe the exponential growth phase

Answer 5

has all the nutrients it needs so keeps growing

Question 6

Describe the stationary phase

Answer 6

bacterial growth and decline equals out

Question 7

Describe the death phase

Answer 7

-nutrients becomes limited/waste product builds up to bacteria dying
-longest phase

Question 8

In the stationary phase, ________ ____ are created that go into starvation mode

Answer 8

persister cells

Question 9

What do chaperone proteins do during the death phase?

Answer 9

protect DNA and bind enzymes to prevent denaturing

Question 10

What is the advantage of the viable counting method?

Answer 10

bacterial colonies are easier to count

Question 11

T/F: For viable counts, you should use the highest dilution to count colonies.

Answer 11

F: lowest dilution for a countable range of 30-300 colonies

Question 12

What are the advantages of using the direct (total) cell count method?

Answer 12

-higher count
-can pick up more bacteria
-can count dead/alive cells
-faster

Question 13

T/F: A spectrophotometer and a standard curve are needed to correctly measure turbidity.

Answer 13

T

Question 14

What is a flow cytometer?

Answer 14

uses hydrodynamic focusing to get a very thin line of the sample and lets one cell through at a time