Growth of Bacteria Dr Pettit

Question 1

Name the 4 phases of the ‘bacterial growth curve.’ Is the bacteria population stagnant, growing, or declining in each of these phases?

Answer 1

lag: stagnant
log: growing
stationary: stagnant
death: declining

Question 2

What are secondary metabolites and why are they released during the stationary phase?

Answer 2

e.g. toxins

Bacterial cells synthesize these chemicals in an effort to bolster their #s in response to a stagnating population.

Question 3

APT are only generated during one phase of fermentation. Name the phase. How many ATP are produced?

Answer 3

Glycolysis: 1-2 ATP

Question 4

T or F: As a rule, bacteria that use cellular respiration grow faster and replicate faster than bacteria that use anaerobic respiration or fermentation.

Answer 4

T.

bacteria that use cellular resp. grow fastest and bacteria that use fermentation grow slowest.

Question 5

Describe what it means for biofilms to ‘mixed’ and ‘heterogeneous.’

Answer 5

• mixed: different species (many kinds of bacteria, fungus, etc) are often in the same biofilm
• heterogeneous: within one matrix, you can have some areas with different pH, different O2 amounts, different nutrient concentrations, etc

Question 6

T or F. Because biofilms are a highly concentrated group of bacteria confined to a small area, they make easy targets for antibiotic therapy.

Answer 6

F.
biofilms are a concentrated group of bacterial cells, but they have several mechanisms for antibiotic repentance (i.e. they’re mixed, they contain persister cells, biofilm bacteria are slow-growth, close living quarters makes for easy and frequent antibiotic resistance gene exchange)