Bacterial Growth

Question 1

By what process do bacteria divide?

Answer 1

binary fision

Question 2

By what process do eukaryotes divide?

Answer 2

cell cycle

Question 3

How do biofilms form?

Answer 3

1. Attachment (reversible)
2. Cell-cell adhesion (irreversible)
3. Proliferation
4. Maturation
5. Dispersion

Question 4

What is a single colony?

Answer 4

It is a colony that comes from a single cell that undergoes multiple divisions

Question 5

How can you store cultures?

Answer 5

1. Agar slants
2. Freezer cultures (needs a cryoprotectant)
3. lyophilized powder (freeze-dried)

Question 6

What do cryoprotectants do?

Answer 6

Slow down crystal formation, a common one is glycerol

Question 7

What can affect bacteria growth?

Answer 7

1. Temperature
2. Oxygen
3. pH
4. Osmolarity

Question 8

How are bacteria separated based on temperature preferences?

Answer 8

1. Psychrophile
2. Psychrotroph
3. Mesophile (associated with animals)
4. Thermophile
5. Hyperthermophile

Question 9

What can you use to look at oxygen preferences?

Answer 9

shake tubes or fluid thioglycollate medium

Question 10

How are bacteria separated based on oxygen preferences?

Answer 10

1. Obligate anaerobe (only oxygen)
2. Facultative anaerobe (prefer oxygen)
3. Obligate anaerobe
4. Microaerophile (small amounts of oxygen)
5. Aerotolerant (don’t use oxygen for respiration)

Question 11

What is catalase?

Answer 11

An enzyme that converts H2O2 into O2 and H2O

Obligate aerobes, facultative anaerobe, and microaerophile (in small amounts) make these

Question 12

What is superoxide dismutase?

Answer 12

Enzyme that converts superoxide (O2-) and H into H2O2
Obligate aerobes, facultative anaerobes, microaerophiles, and aerotolerant make these

Question 13

How are bacteria separated based on pH preferences?

Answer 13

1. Acidophiles (pump out excess H+)
2. Neutrophiles
3. Alkalophiles (use Na+ gradient)

Question 14

Why is osmolarity of environment important?

Answer 14

1. avoid lysis (burst)
2. avoid plasmolysis (shrink)

Question 15

How can you avoid plasmolysis?

Answer 15

1. synthesize osmoprotectants (proline, trehalose)
2. “adsorb” salt

Question 16

What is needed for metabolism?

Answer 16

1. Elements
2. Growth factors

Question 17

What elements are needed for metabolism?

Answer 17

C, H, O, N, P, S
K+, Mg++, Ca++ (protein folding)
Fe++

Question 18

Chemotroph vs phototroph

Answer 18

Chemotroph: get energy from free energy of redox reactions
Phototroph: get energy from sunlight (photosynthesis)

Question 19

Heterotroph vs autotroph

Answer 19

Heterotroph: get carbon from organic compounds
Autotroph: fix carbon from atmospheric CO2

Question 20

Organotroph vs Lithotroph

Answer 20

Organotroph: gets electrons from reduced organic compounds
Lithotroph: get electrons from reduced INorganic compounds

Question 21

What is defined media?

Answer 21

all ingredients can be listed by chemical formula and by amount

Question 22

What is complex media?

Answer 22

at least one ingredient is not defined, often contains “extracts” of various things

Question 23

What is specialty media?

Answer 23

media that prevents the growth of some organisms (ie. salt and antibiotic agars)

Question 24

What is differential media?

Answer 24

media that looks different with different organisms (ie. blood and MacConkey’s agar)

Question 25

How can you grow anaerobes?

Answer 25

A) in anaerobic (gas-pak) jars
B) in glove boxes

Question 26

How can you grow obligate intracellular parasites?

Answer 26

A) in tissue cultures
B) in embryonated eggs

Question 27

How can you grow unculturable bacteria?

Answer 27

A) in iChip plates
B) in microdroplets

Question 28

What are enrichment cultures?

Answer 28

specially designed medium that allows one organism to grow better than others