key area 2.6 - environmental control of metabolism Flashcards
1
Q
examples of microorganisms
A
- archaea
- bacteria
- some eukaryotes such as yeast
2
Q
why is using microorganisms useful?
A
- highly adaptable due to wide range of niches
- can use a variety of substrates for their metabolism
- easy to culture, they reproduce and grow quickly
- cheap food substrate
- produce many different products
- metabolism can be controlled and manipulated easily
3
Q
biosynthesis
A
- building up of a complex molecule from simpler ones
- molecules required for biosynthesis in microorganisms include: amino acids, vitamins and fatty acids
4
Q
growth medium
A
- substance used to culture microorganisms
- nutrient agar - solid jelly which microbes grow on the surface of
- broth - nutrient rich liquid used in industrial fermenters
5
Q
fermenter
A
- container used to culture microorganisms on a large scale to obtain a useful product
- conditions such as temperature, pH, oxygen and glucose concentration are controlled by computers to keep them at their optimum
6
Q
composition of growth media
A
- require an energy source and a supply of raw materials in their growth medium
- raw materials used for biosynthesis
- many organisms produce all complex molecules needed for biosynthesis, others require specific complex compounds such as vitamins or fatty acids to by supplied in growth media
- energy source derived from either chemical substrates such as carbohydrates or from light in the case of the photosynthetic organisms
7
Q
culture conditions
A
- sterility - eliminate competition with other microorganisms used in the process and reduce the risk of spoilage of the product
- temperature
- oxygen
- pH - buggers or the addition of an acid or alkali
8
Q
growth
A
- irreversible increase in dry biomass
- occurs when the rate of synthesis or organic material exceeds the rate of breakdown of material
9
Q
generation time
A
- time it takes for a unicellular organism to divide into two
10
Q
viable cell count
A
- counts only living microorganisms
11
Q
total cell count
A
- counts viable and dead cells
12
Q
lag phase
A
- cells adjust to growth medium and new conditions
- begin to metabolise substrate, induces enzymes and prepare for division by making energy available
- little to no increase in cell number
13
Q
exponential/log phase
A
- maximum/ most rapid growth of microorganism due to plentiful nutrients
14
Q
stationary phase
A
- cell production and death of cells are equal - steady population
- reduction in availability of nutrients and build up of toxic metabolites
- secondary metabolites may also be produced enabling the outcompeting of other microorganisms used
15
Q
death phase
A
- lack of nutrients or oxygen and accumulation of toxic metabolites increases death rate reducing population
