Chapter 4 - Dynamics of Prokaryotic Growth Flashcards
How do prokaryotic cells divide?
binary fission
What is exponential growth?
the population doubles after each division
What is the generation time?
The time it takes to double
What are biofilms?
polysaccharide-encased communities that bacteria live in
Describe the formation of biofilm.
- Bacteria adhere to a surface
- They multiply and produce extracellular polymeric substances (EPS)
- Other bacteria may attach to the EPS
- Cells communicate and create channels to pass nutrients and waste
- Some cells detach and move to other surfaces to start the process over
What are closed systems?
Prokaryotes grown on agar plates or in broth
What are closed systems called?
Batch cultures
What are characteristics of closed systems?
nutrients not renewed, wastes not removed, yields characteristic growth curve
What are the 5 stages of a growth curve?
- Lag phase
- Log or exponential phase
- Stationary phase
- Death phase
- Phase of prolonged decline
What stage are bacteria the most susceptible to antimicrobial compounds?
Log phase due to the synthesizing of antibiotic targets (enzymes, ribosomes, etc.)
What are characteristics of colonies grown on plates?
Edge of colony has O2, nutrients
Center has depleted O2, nutrients
toxic wastes accumulate in the center
exponential phase at edge and death phase in center
What is the optimal temperature of Psychrophiles?
Where are they found?
-5˚C ~ 20˚C
antarctic and arctic regions
What is the optimal temperature of Psychrotrophs?
What are they important in?
0˚C ~ 35˚C
food spoilage
What is the optimal temperature of Mesophiles?
What are the major harmful bacteria in this species?
15˚C ~ 45˚C
Pathogens (37˚C)
What is the optimal temperature of Thermophiles?
Where are they found?
40˚C ~ 80˚C
hot springs