Lab 5

Question 1

What are the phases of growth

Answer 1

lag phase, log phase, stationary phage and decline

Question 2

Whats the direct method

Answer 2

Total count
+ direct count
+ viable count

Question 3

Whats direct count

Answer 3

measuers all the cells in the culture by microscopy (both viable and non viable)

Question 4

Whats viable count

Answer 4

determined by spreading appropriate diluitons of bacterial culture into solid mediuma nd allow to grow

Question 5

How much bacteria should be present for tuburdity to work

Answer 5

10^7 bacterial cells/milimeter must be present

Question 6

Why is turbidity only considered an indirect method

Answer 6

• Changes in cell mass
• Different strains have different cell sizes
• Cell size varies with phisiologival conditions

Question 7

Generation time formula

Answer 7

0.3/slope

Question 8

Turbidity measures the

Answer 8

total cell population (both viable and non viable)

Question 9

Turbidity?

Answer 9

Turbidity is due to light scattering.
Both viable and non-viable cells scatter light, so turbidity measures the total cell
population.

Question 10

How to calculate the Original cell density from a petroff houser tchmaber

Answer 10

of cells counted/ (# of squares) x (dilution factor) x (volume)

Question 11

Whats the dilution factor in petroff houser tchmaber

Answer 11

volume of cells/ total cell mixture (cell + dye)