microbiology Flashcards
1
Q
gram positive bacteria
A
- thicker peptidoglycan layer
- no lipopolysaccharide (vulnerable)
- retains crystal violet
- stains purple
2
Q
gram negative bacteria
A
- thinner peptidoglycan layer
- lipopolysaccharide present (protects)
- lipopolysaccharide prevents uptake of CV
- stains red
3
Q
conditions
A
carbon- respiration
nitrogen- synthesis of nucleotides
temp- 25-45 (mammalian 37)
pH- slightly alkaline
4
Q
shape
A
bacillus-cylindrical
coccus-spherical
spirillium-rod
5
Q
staining method
A
- bacteria on slide+heat fix
- crystal violet bind to peptidoglycan
- lugs iodine to fix stain to peptidoglycan
- decolourise with ethanol
- counter stain with safranin
6
Q
lag
A
- slow growth
- adaptation
7
Q
log
A
- no limiting factors
- few toxic by products
- plenty of nutrients
- rapid
8
Q
stationary
A
birth rate=death rate
-reduced resources
9
Q
death
A
-death rate higher than birth rate
