genetic variation

• • A mutation is where the base sequence of DNA is changed.
  • Substitution is where a bases is substituted for another
  • Deletion is where a base is deleted from the sequence
  • Addition is where a base is added to the sequence
  • Deletion and addition will result in a frame shift mutation. This is more dangerous to organisms because the protein formed may be radically different from the intended one.
• A polygenic trait is controlled by a large number of genes
• Discontinuous variation – data that has a limited set of values i.e. clear cut groups
• Continuous variation – data can be any value in a continuous range i.e. large range of potential values
• • Genetic variation is variation inherited from parents.
  • Environmental variation is variation caused by the environment the organism lives in.
  • In reality almost all phenotypic features are a mixture of both, though there are some that are purely genetically controlled or environmentally controlled.