Genetic control of metabolism in microorganisms Flashcards
Why are micro-organisms used for research or industry?
They are easy to culture, reproduce and grow quickly, food substrate often cheap, produce useful products, can easily manipulate their metabolism
What are two types of growth mediums commonly used in the lab?
Nutrient agar and nutrient broth
What techniques are used when culturing micro-organisms to maintain sterile conditions?
Aseptic techniques
Why is it important to maintain sterile conditions when working with micro-organisms?
To prevent contamination which could affect the growth of the microorganism
Which piece of machinery is used when culturing micro-organisms on a large scale?
Fermenter
Which factors can affect the growth of micro-organisms?
Temperature, oxygen concentration, pH, glucose concentration
What is provided to micro-organisms in a simple growth media?
Energy source (if not photosynthetic) and simple chemical compounds for biosynthesis of molecules required for growth.
Why do some micro-organisms require more complex growth media like beef extract?
They are unable to synthesis molecules necessary for growth without extra vitamins and fatty acids.
What can be used to control pH in an experiment /fermenter?
Buffers
What are the four phases of microbial growth?
Lag phase, log phase, stationary phase, death phase.
What is meant by “doubling time” or “generation time” in terms of growth of micro-organisms?
The time needed for a population to double
What happens during the lag phase?
Micro-organisms induce enzymes required for growth and synthesis molecules necessary for growth.
What happens in the log phase?
The cells divide at their maximum rate
What happens during the stationary phase?
The birth rate = the death rate due to nutrients running out and a build-up of secondary metabolites, some of which are toxic
What happens in the death phase?
Toxic metabolites and lack of substrate leads to more cells dying than are being produced.
What is a viable cell count?
The number of cells that are alive and capable of reproducing.
What is the total cell count?
All cells dead and alive.
What happens during primary metabolism?
Breaks down substrate to obtain energy and produces primary metabolites essential for growth.
What happens during secondary metabolism?
Results in secondary metabolites which may provide an ecological advantage but is not necessary for growth e.g. Antibiotics.
When does secondary metabolism occur?
At the end of the stationary phase
How can we manipulate the metabolism of micro-organisms in culture?
Add precursors, add inducers, add inhibitors
