2.6 Environmental Control of Metabolism Flashcards
3 domains of life
- archaea
- bacteria
- some eukaryotes
of the 3 domains of life, microorganisms can belong to..
all 3
microorganisms use … for metabolism and produce …
a wide variety of substrates and produce a range of products
microorganisms are used in industries because (3)
- ease of cultivation
- speed of growth
- adaptability
to be cultured, microorganisms must be provided with what? (2)
- appropriate growth medium
- carefully controlled environmental factors
growth media
the substance that microorganisms are grown on
what does growth media contain?
- raw materials
- an energy source
examples of complex molecules required by microorganisms (3)
- amino acids
- vitamins
- fatty acids
energy sources (2)
- chemical substrates
- light (in photosynthetic organisms)
conditions that have to be controlled when culturing (4)
- sterility
- temperature
- oxygen levels
- pH
why are sterile conditions required when culturing? (2)
- reduces competition for nutrients with the desired microorganism
- reduces risk of spoilage
phases of microorganism growth (4)
- Lag
- Log (exponential)
- Stationary
- Death
Lag phase
enzymes are induced to metabolise substrates
log/exponential phase
most rapid phase of growth due to plentiful nutrients
stationary phase
- nutrients in growth media become depleted
- there is s build up of toxic metabolites
- secondary metabolites produced
secondary metabolites
in the wild, they provide an ecological advantage as they allow the microorganism which produces them to outcompete others
in what stage are secondary metabolites produced?
stationary
example of a secondary metabolite
antibodies
death phase
occurs because of toxic accumulation of metabolites and a lack of nutrients
viable cell count
only count the living microorganisms
total cell count
count both living and dead microorganisms
which type of cell counts shows the death phase and why?
viable cell count, as viable cell numbers are decreasing
