ENVIRONMENTAL CONTROL OF METABOLISM U2 Flashcards
State 3 groups of micro-organisms and explain why they are used in biotechnology
Micro-organisms include:
Archaea
Bacteria
Some eukaryotes.
Micro-organisms use a wide variety of substrates for metabolism and produce a range of products from their metabolic pathways.
Example: the use of yeast in the production of alcohol and bread-making.
Micro-organisms are used because of their adaptability, ease of cultivation (easily grown) and speed of growth.
Describe how a micro-organism obtains raw materials for growth and as a source of energy
A growth media will provide the micro-organism with raw materials for biosynthesis as well as an energy source.
Many micro-organisms produce all the complex molecules required for biosynthesis, for example amino acids, vitamins and fatty acids. Other micro-organism requires these to be supplied in a growth media.
The energy source is derived either from chemical substrates or from light in photosynthetic organisms.
State 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.
Explain why fermenters should be sterile
Sterile conditions are needed in fermenters to:
Reduce competition with desired micro-organisms for nutrients.
Reduce the risk of spoilage of the product.
Describe and explain the phases of growth of micro-organisms
The lag phase is where the enzymes are induced to metabolise substrates.
The log/exponential phase contains the most rapid growth of micro-organisms due to plentiful nutrients.
The stationary phase occurs due to the nutrients in the culture media becoming depleted and the production of toxic metabolites. (secondary metabolites)
Death phase occurs due to toxic accumulation of metabolites or the lack of nutrients in the culture.
Describe an example of a secondary metabolite produced and its advantage 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.
Interpret growth curve of micro-organisms
Use semi-logarithmic scales in producing and interpreting growth curves.
State the difference between viable cell counts and total cell counts
Viable cell counts involve counting only the living micro-organisms.
Total cell counts involve counting viable and dead cells.
Only viable cell counts show a death phase where cell numbers are decreasing.
