2.6 Environmental Control of Metabolism Flashcards
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
Describe the Log/Exponential phase
Highest Rate of growth , microbe number is rapidly increasing
Describe the Stationary Phase
Growth rate is equal to the death rate, culture has run out of substrates and secondary metabolites are being produced
What is primary metabolism of a microorganism?
Occurs during lag and log phase
Breaks down available substrate to obtain energy
Produces primary metabolites that can be used for biosynthesis
What does primary metabolism produce?
Primary metabolites that can be used for biosynthesis
Give an example of a secondary metabolite that can confer an ecological advantage
Antibiotics
<ul>
<li>Inhibits the growth of other species of microorganisms and so reduce competition</li>
</ul>
What is secondary metabolism of a microorganism?
Occurs at the end of log phases and produces substances that are not associated with growth
What are the three molecules that can be added to control metabolism?
Inducers
Inhibitors
Precursors
Define what an Inhibitor does
Prevents the breakdown of a desired product
Define the function of an Precursor
Acted on by an enzyme leading to the product of a desired product
Define the role of an Inducer
Triggers the production of a specific enzyme
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