2.6 Environmental Control of Metabolism Flashcards
(35 cards)
What are the three domains of life?
Prokaryotes, Eukaryotes, Archaea
Why are microorganisms useful in research and industrial processes?
- cheap food substrate
- grow fast
- easy to cultivate
What do microorganisms need to survive?
Energy source and raw materials for biosynthesis
Give examples of molecules that microbes can be used to produce
Amino acids, vitamins, nucleic acids
If a micro-organism is photosynthetic where can they get their energy source?
Light energy
Chemical Substrates
What are examples of complex additional compounds that may be added to growth medium of cells?
Fatty Acids
Beef Extract
What four factors must be monitored when culturing cells?
- Sterility
- Temperature
- Oxygen Concentration
- PH
(STOP)
State two ways that contamination could be prevented
Heat Sterilisation (using an autoclave) Chemical Sterilisation (Disinfectants, Antiseptics)
What is an ‘Obligate Aerobe’
A microbe that requires a constant supply of oxygen
How can oxygen be supplied to a growth medium?
Aeration - oxygen is pumped into a liquid culture
Define ‘Sterile’
Free from contamination
Why is making the culture sterile important?
Contaminating Micro-organisms may compete for resources and limit the growth of culture and so this must be resolved
Why is a temperature an important factor to be controlled?
Important to ensure enzymes are working at their optimum in order to achieve the maximum growth rate
How is temperature monitored in a culture?
Using a thermometer
How can the temperature be decreased in a culture?
When microbes respire they release heat energy
Vessel is cooled by allowing cold water to flow over the outer surface of the fermentation tank
Define ‘growth’
Growth is the irreversible increase in dry biomass of an organism
Define growth of a yeast colony
Increase in cell number
What is ‘Generation Time’?
Number of time taken for one cell to divide into two daughter cells
What is the difference between the total cell count and the viable cell count?
Total cell count - number of cells visible in field of view(dead or alive)
Viable cell count - number of cells that are alive
What is used to count the total cell count and the viable cell count?
Haemocytometer
What is trypan blue stain used for?
To identify the dead cells in a colony
What are the four stages in the growth of a microorganism?
Lag
Log/Exponential
Stationary
Death
Describe the Lag phase
Microbes are adjusting to condition
Producing enzymes to metabolise available substrates
Describe the Death Phase
No substrate is left and toxic metabolites are building up causing the death rate of cells to increas
- Inhibits the growth of other species of microorganisms and so reduce competition
