Exam 1 Lecture 8

Question 1

How is prokaryotic growth defined?

Answer 1

An increase in cell numbers= increase in biomass

Question 2

What is needed for cell growth?

Answer 2

Energy and nutrients

Macronutrients and Micronutrients

Good environment

Question 3

Macronutrient examples?

Answer 3

C, O, N, H, P, S

Cations- MG++, Fe++, Ca++, K+, Na+

Question 4

Micronutrient Examples?

Answer 4

Mn, Zn, Co, Mo, Ni, Cu and other vitamins and cofactors

Question 5

How do they measure bacterial growth?

Answer 5

Direct cell counting

Can put a measured amount of suspension media on a plate and count colonies

Or monitoring turbidity

Turbidity is a measure of the degree to which the water loses its transparency due to the presence of suspended particulates.

Question 6

Name the 4 bacterial growth phases?

Answer 6

1. Lag (no growth adjusting to the new environment for a short time)
2. Log (exponential- plenty of nutrients)
3. Stationary (Nutrients running low)
4. Death (no nutrients left in media)

Gene expression is adjusted according to stage

Question 7

5 environmental factors that affect cell growth?

Answer 7

Temperature (covered later)

pH (alkaliphile, neutralophile, and acidophile)

Osmolarity (salt usually) (halophile and halotolerant)

Oxygen (Covered later)

Pressure (barophile, barotolerant)

Question 8

4 different groups of bacteria that tolerate different temperatures and their temp ranges?

Answer 8

1. Psychrophile (10-20 C)
2. Mesophile (15-45 C)
3. Thermophile (50-80 C) Only Prok and Arch over 65 C
4. Extreme Thermophile (65-90 C) Only Arch over 90 C

Question 9

In a test tube what are the different layers of O2 availability?

Answer 9

High at top - Aerobic

Low in middle - microaerophilic

No at bottom- Anaerobic

Question 10

Types of O2 tolerant bacteria?

Answer 10

1. Obligate aerobe
2. Microaerophiles
3. Facultative microbes/anaerobes also know has aerotolerant anaerobes
4. Obligate anaerobes

Question 11

A big example of well known facultative(either low or high O2) microbe?

Answer 11

E. Coli -glycolysis or fermentation

Question 12

E coli doubling time in O2 rich media and O2 minimal media?

Answer 12

20 mins versus 60 mins

Question 13

What passes freely through membranes?

Answer 13

Only uncharged non-polar- H2O, O2, NH3, CO2, H2

The rest need transport systems

Question 14

How do symporters work?

Answer 14

Two molecules move in the same direction, one going along its gradients take another with it against its gradient

PMF -LacY- H+ and lactose in E coli

Not always PMF

Question 15

How do antiporters work?

Answer 15

While one molecule moves down its gradient and another is passed against its gradient in opposite direction.

Example in E coli H+and tetracycline

Question 16

How do ABC transporters work?

Answer 16

Use ATP hydrolysis inside a cell on the transporter to power it.

Often use solute binding or escort proteins (siderophores) to bring the solute/nutrient needed to the transporter for transport into the cell

Used for sugars and amino acids or iron

Example- E coli maltose transporter

Question 17

How do PTS (Group translocation/phosphotransferase systems work?

Answer 17

Use PEP to add phosphate to sugars or other modifications to substrate during transport across the membrane into the cell

E coli and glucose to glucose-6-phosphate setting it up for glycolysis

Question 18

Do cells produce all types of transporter all the time?

Answer 18

No- depends on the environment