Bacteriology: structure, function, classification Flashcards
1
Q
What are prokaryotes?
A
- archaea
- bacteria
2
Q
What are eukaryotes?
A
- eucarya
- (nucleated, organelles)
3
Q
What are some examples of distinguishing features of bacteria?
A
- morphology
- microscopy
- colony
- staining characteristics (gram)
- growth requirements
- toxin and enzyme production
- response to phages or antimicrobials
- presence/ absence of surface/ antigenic structures
4
Q
How do bacteria replicate?
A
- binary fission
- haploid
- DNA is replicated
- then the cell membrane is elongated and the 2 DNA molecules separated
- cell wall forms and cell membrane invaginates
- cross wall forms completely
- then get 2 daughter cells
5
Q
What are the different phases in the growth curve?
A
- lag phase - preparing for the exponential growth
- log phase - bacteria divide as quickly as they can
- stationary phase - growth is equal to death - nutrients are depleting
- death phase - die due to no nutrients left/ oxygen used up
- long-term stationary - not all die
6
Q
What are the categories of bacteria?
A
- bacilli - rods
- cocci - spherical
- staphylococci - bunch of grapes
- streptococci - long line
- spirochaetes
- vibrios - comma
7
Q
A
8
Q
How are endospores formed?
A
- DNA replication in vegetative cell
- DNA lines up along long axis
- cell membrane invaginates inside to form forespore
- the cell membrane grows and engulfs the forespore in a secondary membrane
- vegetative DNA disintergrates
- a cortex of calcium and diplicolinic acid is deposited between membranes
- spore coat forms around endospore
- maturation of endospore - completion of spore coat - increased resistance to heat etc.
- endospore released from cell
9
Q
What are the different bacteria staining techniques?
A
- Gram staining
- +ve/-ve
- based to crystal violet staining and counterstaining
- heat fixation
- Diff Quick
- rapid - morphology
- wet fixation
- Specific
- ZN - mycobacteria
- silver - spirochaetes
10
Q
How is gram staining done?
A
- heat fixation
- crystal violet - stains everything (peptidoglycan)
- iodine - traps the cv in cell - stays in the gram +ve cells
- alcohol wash - washes cv out of gram -ve cells - but it is trapped in the gram +ve due to iodine
- safranin - counterstaining - gram -ve = pink, gram +ve = purple
11
Q
Why is staining different between gram +ve and -ve?
A
- gram +ve- have thick peptidoglycan layer and a single cell membrane - peptidoglycan binds cystal violet
- gram -ve - inner and outer protective membrane, thick peptidoglycan layer - no trapping of cv to peptidoglycan
12
Q
Role of peptidoglycan?
A
- gives rigidity to bacterial cell
- assists in preventing phagocytosis
- pyrogenic properties (fever)
- degraded by lysozyme
13
Q
How to do Diff quick staining?
A
- one drop on slide - allow to air dry briefly
- place in fixative
- solution 1
- solution 2
- distilled water wash
14
Q
What are the different types of growth media?
A
- nutrient media (slower growth)
- nutrient agar
- Mueller Hinton
- enriched media - fastidious organisms
- blood/ serum agar (whole blood, lysed blood, serum)
- electron acdeptors, energy sources
- selective media
- supplemented plates e.g. antibiotics (camp)
- differential use of nutrients (fermentation of sugars)
- MacConkey agar
15
Q
Name the gas conditions
A
- oxygen
- aerobic
- facultative anaerobic - survive in both but sometimes will need electron acceptors to survive without oxygen
- microaerobic - camp
- co2
- all organisms
- capnophiles - >5%
- hydrogen
22
Q
How do you plate out?
A
- flame the loop
23
Q
What are the different types of hemolysis?
A
- beta = complete
- alpha = partial
- gamma = none
