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  • Created by: tiacoles
  • Created on: 11-04-16 17:28

Biotechnology is the industrial use of living organisms, or parts of living organisms, to produce food, drugs or other products. 

Microorganisms are often used in industrial processes because they:

  • are highly versatile, occupying a wide range of habitats, including extreme conditions 
  • have a rapid growth rate
  • are small, and can be produced in large numbers in a small volume
  • can be grown in the laboratory, so are not influenced by climate
  • produce more enzymes per unit mass than larger organisms
  • can be genetically manipulated to express genes for novel products or human biochemicals
  • can be manipulated to produce secondary metabolites on demand. 

Growth of a microorganism in closed culture

Bacteria multiply by binary fission, in which one cell divides into two daughter cells, doubling the number of cells every generation. The time taken for a bacterial population to double is called its generation time. Under optimal conditions, some bacteria can divide as frequently as once every 20-30 minutes. There are always factors preventing unlimited population growth:

  • depletion of nutrients
  • depletion of oxygen
  • accumulation of toxic or acidic waste products

These limiting factors are density dependent: the greater the number of individuals in the population, the greater the effect of factor. 

There are four recognisable phases of population growth:

  • Lag phase: the bacteria adjust to new conditions, synthesising carriers to absorb nutrients of enzymes to digest them. This may involve switching on genes. Growth is slow. 
  • Exponential phase (logarithmic phase): the numbers of bacteria double in each unit of time. The geometric growth


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