Bacterial Physiology Flashcards
binary fission
the way which bacteria reproduce
Does bacteria grow linearly or exponentially?
exponential growth
mass of one bacterial cell
generation (doubling) time
the amount of time required for one bacterium to become two
Typical generation time for medically important bacteria under ideal conditions?
20 minutes
Are Mycobacterium notoriously fast or slow replicators?
slow - 20 hours to 20 days!
Generation time for Clostridium perfringens?
~6 minutes
4 Parts of the Sigmoid Growth Curve
- Lag phase
- Logarithmic phase
- Stationary phase
- Death/decline phase
Lag phase
time for bacteria to adjust to a new environment; maturing but not yet able to divide; synthesis of molecules does occur
Logarithmic phase
period characterized by cell doubling (exponential)
Stationary phase
growth and death rate are equal here
due to depletion of a necessary nutrient or formation of inhibitory product
Death/Decline phase
bacteria die due to too many toxins, lack of nutrients, temperature out of survival range, host immune response, etc.
One (1) Colony on an Agar Plate is a result of how many cell divisions?
20-30 cell divisions of a single cell - can be more than a billion bacteria!
Typical optimal pH requirements?
between 7.2 and 7.6
Typical optimal temperature requirement for growth of most pathogenic bacteria?
37 C
Methods used to control bacterial growth?
refrigeration and sterilization by heat
Will heat kill spores?
no guarantee, they’re hardy little buggers
psychrophile
capable of reproduction at low temperature (10 C)
mesophile
grows best in moderate temperature (37 C, majority of microbes)
thermophile
grows best at higher than normal temperature (65 C)
hyperthermophile
very high thermostability (over 90 C)
heterotroph
must ingest biomass to grow, and that biomass can be converted to the essential nutrients of carbon, nitrogen, cofactors, etc.
cyanobacteria
able to carry out photosynthesis and can sustain themselves
prototrophs
WILD-TYPE bacteria that can synthesize all compounds needed for growth from simple ingredients