Environmental control of metabolism
6 Environmental control of metabolism
Microorganisms to include archaea, bacteria and some species of eukaryota.
(a) Variations in growth media and control of environmental factors.
Microorganisms require an energy source (chemical or light) and simple chemical compounds for biosynthesis. Many microorganisms can produce all the complex molecules required, including amino acids required for protein synthesis. Other microorganisms require more complex compounds to be added to the growth media, including vitamins and fatty acids. Culture conditions include sterility to eliminate any effects of contaminating microorganisms, control of temperature, control of oxygen levels by aeration and control of pH by buffers or the addition of acid or alkali.
(b) Phases of growth and doubling or generation time of exponential growth and changes in culture conditions. Phases to include lag (enzymes induced), log/exponential, stationary (culture depleted and secondary metabolites produced) and death (lack of substrate and toxic accumulation of metabolites). Viable and total cell count.
(c) Control of metabolism through the addition of metabolic precursors, inducers or inhibitors to give a required product. Secondary metabolism can confer an ecological advantage by producing substances not associated with growth.
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Homework Sheets : CfE Higher Sht2_14
