Bacterial Growth Flashcards
Name types of cell division (5)
Binary fission, cell shape dependant division, budding, filamentous growth,baeocytes
Steps of binary fission?
Chromosome replication and septum formation/ cytokinesis
Why are Z ring only at cell centre?
Because Fts Z protein polymerisation (of which Z ring is made) is inhibited by MinC which is highly concentrated at the cell poles
Filamentous growth is division typical of
Fungi, actinomycetes
Which are the phases of bacterial growth ?
Lag phase
Exponential phase
Stationary phase
Death phase
Long term stationary phase
What occurs in stationary phase? (3)
1) no change in viable cell number
2) biomass weight is constant
3) antibiotics production and sporulation
What is the growth rate? (2 def)
Growth rate indicated by k is the time it takes for a cell to double.
It’s the generations number per unit time
What’s the growth rate equation?
Nt = N0 2^n
What’s the generation time?
The reciprocal of the growth rate
In which one and only phase can the growth rate be calculated?
Only in exponential phase
Is the growth rate fixed?
No it varies according to species and environment conditions
Which are environmental growth conditions affecting the growth rate? (6)
1) temperature
2) pH
3) water activity/ solute concentration
4) radiations
5) pressure
6) oxygen
Which is the test to distinguish between for groups of bacteria basing on oxygen tolerance?
Thioglycollate test
Why can’t strict anaerobes withstand oxygen?
Because they lack enzymes to detoxify oxygen species ( superoxide dismutase, catalase and peroxidase)
What is the classification of microbes basing on temperature resistance?
psychrophiles, mesophiles, thermophiles, hyperthermophiles
