Bacterial physiology Flashcards
How does bacterial growth occur?
- asexual replication
- occurs by binary fission
- single bacteria divide to produce two daughter cells
- bacteria population double in each replication round
One bacteria can generate many = source of infection - how fast can fast growth bacteria replicate?
- every 10-15 minutes
Describe the steps in binary fission?
- cell replicates its entire DNA - including plasmids
- the cytoplasmic membrane elongates separating DNA molecules
- DNA molecules separate into individual entities and move towards poles
- cross wall forms, membrane invaginates
5/ cross wall forms completely - daughter cells are formed
What does growth by binary fission mean for cell mass?
- means cell mass doubles each generation
What can bacterial growth time be measured in?
- generation time
- population doubling time
How quickly does E.coli double?
- every 20 minutes
How quickly does M.bovis double?
- every 20-24hrs
How often does M. leprae double?
- every 20 days!!
What affect does bacteria doubling time have?
- has an impact in treatment and culturing methods
What are the minimum nutritional requirements for bacteria?
- water
- carbon source to generate proteins and ATP
- nitrogen source
- inorganic salts
What can autotrophs do?
- synthesise own organic compounds
What can heterotrophs not do?
- cannot synthesise own organic compounds
Some heterotrophs are pathogenic - what are some examples?
- Pseudomonas spp.
- Klebsiella spp.
- Escherichia spp.
- Salmonella spp.
- Campylobacter spp.
What have heterotrophs evolved to do?
- host-pathogen co-evolution (reliance) = leads itself to infectious disease
What are autotrophs’ typically?
- non-pathogenic
- clostridium difficile
What can labs use to cultivate bacteria?
- liquid media and solid media (agar)
Not all bacteria will grow on the same media - what may we need to supplement them with?
- blood products
- salts to cultivate bacteria outside of host
What is the general temperature bacteria need to grow?
- 37 degrees
- species differences as they grow at body temp of host