Bacterial Growth

Question 1

List the different oxygen requirements of different bacterial species.

Answer 1

Strictly (obligate) aerobic

Microaerophilic

Facultatively anaerobic

Strictly anaerobic

Question 2

What are the three mechanisms of nutrient uptake?

Answer 2

Passive diffusion, facilitated diffusion, active transport

Question 3

What products can be produced from fermentation?

Answer 3

Acids, CO2, H2, Alcohols, ATP/NADH2/NADPH2

Question 4

What products can be produced from respiration?

Answer 4

CO2, ATP, NADH2 + NADPH2

Question 5

What are the terminal electron acceptors in aerobic/anaerobic respiration?

Answer 5

Aerobic = O2 -> H2O

Anaerobic = NO3- -> NO2- -> NO -> N2 / SO4(2-) -> H2S / CO2 -> CH4

Question 6

List the different types of culture media and give an example.

Answer 6

Nutritionally simple, e.g. agar

Enriched (non-specific), e.g. blood agar

Selective - inhibition of other bacteria, enrichment of wanted bacteria

Differential, e.g. MacConkey’s bile lactose agar - visual differentiation of bacterial colonies

Question 7

What is the bacterial growth curve in a closed system?

Answer 7

Lag phase: adapting uptake systems and proteins on surface, changing enzymes within them

Logarithmic growth: binary fission (double, double, double)

Stationary phase: growth stops due to lack of nutrients etc.

Death: from starvation/poisoning themselves

Question 8

What is the value of bacterial studies?

Answer 8

Bacterial identification, clinical infection control, vaccine production.