General

• Variation


  Differences in the characteristics of individuals in a population
• Causes of variation within a species

  • Genetics
  • Environment
  • A mixture of both
• Genetic variation

  Variations in the genotypes of organisms of the same species due to the presence of different alleles, creating differences in phenotypes
• What creates genetic variation in a species

  • Spontaneous mutations
  • Sexual reproduction
• Mutation


  A random change to the base sequence in DNA which results in genetic variants, occurring continuously
• Types of gene mutation

  • Insertion
  • Deletion
  • Substitution
• How a gene mutation may affect an organism's phenotype

  • Neutral mutation does not change the sequence of amino acids, no effect on phenotype
  • Mutation may cause a minor change in an organism's phenotype e.g. change in eye colour
  • Mutation may completely change the sequence of amino acids, resulting in a non-functional protein, severe changes to phenotype