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
What is the optimal temperature of Hyperthermophiles?
70˚C ~ 110˚C
found in very hot places, usually members of archaea
How does refrigeration preserve food (4˚C)?
it limits growth and freezing preserves food but doesn’t kill microbes
What is an Obligate Aerobe?
needs O2 and produces superoxide dismutase and catalase
What is an Facultative Anaerobe?
Grows best in O2 but also grows without it
produces superoxide dismutase and catalase
What is an Obligate Anaerobe?
cannot grown when O2 present
does not produce superoxide dismutase or catalase
What is an Microaerophile?
Grows only if small amounts of O2 are present
produces some superoxide dismutase and catalase
What is an Aerotolerant Anaerobe?
Grows equally well with or without O2
produces superoxide dismutase but not catalase
How are superoxide dismutase and catalase used?
SD inactivates superoxide by converting to O2 and H2O2
Catalase converts H2O2 to O2 and H2O but not used in aerotolerant anaerobes (peroxase) and obligate anaerobes typically lack these
What are neutrophiles?
bacteria require range of pH from 5-8
How is food preserved with respect to pH?
Increasing acidity can preserve food
What are acidophiles?
grow optimally at pH below 5.5
What are Alkaliphiles?
grow optimally at pH above 8.5
How do cells maintain a constant internal pH?
pumping protons out in acidic environment or in if in alkaline environment
True or False? All microorganisms require water for growth.
True
What makes water unavailable for cells?
dissolved salts and sugars
if concentration of solute is higher outside cell, water diffuses out (osmosis)
What are halotolerant cells?
cells that withstand high salt (staphylococcus)
What are halophiles?
cells that require high salt concentrations
marine = 3%
extreme = >= 9%
What do heterotrophs use?
organic carbon
What do autotrophs use?
inorganic carbon as CO2
What is the energy source and carbon source for photoautotrophs?
Sunlight and CO2
What is the energy source and carbon source for photoheterotrophs?
Sunlight and Organic compounds
What is the energy source and carbon source for chemolithoautotrophs?
Inorganic chemicals (H2, NH3, NO2, Fe, H2S) and CO2
What is the energy source and carbon source for Chemoorganoheterotrophs?
Organic compounds (sugars, amino acids, etc.) and Organic compounds
