Unit 2 - Metabolism and Survival (Environmental Control of Metabolism) Flashcards
(12 cards)
What are micro-organisms?
Micro-organisms can come from the three domains of life - archaea, bacteria and some species of eukaryote. They are able to metabolise a wide variety of substrates. This allows micro-organisms to survive in a wide range of ecological niches. Micro-organisms are robust enough to be used by humans in research and industry.
What are the benefits of using micro-organisms?
- They are adaptable
- They can be easily cultivated
- They have fast rates of growth
- They produce a wide range of products from their metabolic pathways which can be used for human benefit
How do micro-organisms obtain raw materials for growth and as a source of energy?
In order to grow, micro-organisms require a source of energy and simple chemical compounds (raw materials). These will be used in order to synthesise other more complex molecules necessary for life (this is called biosynthesis). The energy source can either be from light in photosynthesis or chemical substrates. Although some micro-organisms
can produce all the complex molecules required for biosynthesis (e.g. amino acids, vitamins and fatty acids), some need these complex molecules to be added artificially in a growth medium.
What are the conditions needed to culture micro-organisms?
The conditions needed to culture micro-organisms are:
- Sterility
- Control of temperature
- Oxygen levels
- pH
Micro-organisms are grown in fermenters which are specially controlled to provide these conditions.
Why are sterile conditions needed in fermenters?
Sterile conditions are needed in fermenters to:
- Reduce competition with desired micro-organisms for nutrients.
- Reduce the risk of spoilage of the product.
What is the lag phase?
The lag phase is where the enzymes are induced to metabolise substrates.
What is the log/exponential phase?
The log/exponential phase contains the most rapid growth of micro-organisms due to plentiful nutrients.
What is the stationary phase?
The stationary phase occurs due to the nutrients in the culture media becoming depleted and the production of toxic metabolites. (secondary metabolites).
What is the death phase?
Death phase occurs due to toxic accumulation of metabolites or the lack of nutrients in the culture.
What is an example of a secondary metabolite and what advantage does it have in the wild?
Antibiotics are a secondary metabolite. In the wild these metabolites confer an ecological advantage by allowing the micro-organisms which produce them to outcompete other micro-organisms.
What is a viable cell count?
Viable cell counts involve counting only the living micro-organisms. Only viable cell counts show a death phase where cell numbers are decreasing.
What is a total cell count?
Total cell counts involve counting viable and dead cells.
