Week 3 - Microbiology Bacterial Growth and Physiology Flashcards
Bacterial Gowth
Means multiplication… not bacteria getting bigger!
Bacterial repliation is the generation of 2 complete daughter cells from one cell
How to bacteria multiply?
Bionary Fission
Replication of DNA
Polar separation of daughter chromosomes
Generation of the cross-wall
Separation
What are steps of bacterial multiplication?
DNA Replication
Separation of daughter chromosomes
Cross wall generation
Separation
Static Antibiotics
Stops multiplication
Dynamic Antibiotics
…
What is generation time?
The time for one bacterial cell to become two
This is also the time for a number of cells in a culture to double
What is doubling time?
Generation time
Bacteria in abcess vs bacteria in blood
Bacteria abcess dont grow ast fast so have to have longer acting antibactirea than bacteria in blood (grow really fast…)
What does bacterial growth curve look like?
If there was a slower growing bacteria species the exponential phase would have a lower slope*
Like bacteria growing in blood vs bacteria in an abscess (slower)
Lag phase is when bacteria are adapting to new environment
Log (growth phase) bacteria are doubling!
Stationary phase - nutreints are exahusted, toxins build bacteria remain in constant number
Death phase - toxins kill bacteria (not in all bacteria)
How is this graph different in abcess vs blood?
…
Why want to colonize bacteria?
If someone has UTI.. we want to know how many bacteria are in it… so take sample of urine and colonize it
How to determine bacterial concentration by serial dilution and colony and colony forming units (CFU)?
To determine concentration of bacterial from a liquid culture.. Culture is diluted and plated onto media
Each colony represents ONE bacterium from original culture
For a given culture.. at each time point
Make 10-fold dilutions of a culture
Spread a known volume on an agar plate
Allow colonies to grow
Count number of colonies
Calculate original concentration (at time of sampling)
This only represents LIVE (VIABLE) bacteria
What are growth requirements for bacteria? What does it depend on?
Depends on genetic information in bacteria
All of the elements for organic matter
Ions for energy generation, catalysts, and osmotic maintenance
Energy from Fermentation
Anaerobic bacterial use this.. why? because if they are exposed to O2 they die
The formation of ATP is not coupled to electron transfer (Electron transport chain)
Energy from Respiration
Formation of ATP via oxitative phosphorylation (chemical reduction of an oxidant) where ATP is formed during electron transfer
Energy from Photosynthesis
No medically important bacteria here.
ATP is formed via reduction of an oxidant via light energy
Fermentation
Can use the products of fermentation to identify bacteria**
e
…
What are nutritional requirements for bacteria?
…
Heterotroph
majority of bacteria*
Requires pre-formed organic compounds like sugars, amino acids, and vitamins
Autotroph
Can synthesize everything it needs from inorganic compounds like CO2
Hypotroph
Is an oblicgate intracellular pathogen requiring the host to provide organic compounds - can also be called an intracellular heterotroph
What are three types of bactria based on nutritional req’s?
Heterotroph
Autotroph
Hypotroph
How can bacteria uptake nutrients?
Diffusion through cytoplasmic membrane: Three ways
Carrier mediated diffusion (facilitated diffusion)
Phosphorylation-linked transoprt (group translocation)
Active transport
