GCSE Biology (AQA)

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Variation Arises from Mutation

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Inheritance, Variation and Evolution Variation and Evolution

Variation Arises from Mutation

2:15 Variation and Evolution
Spec 4.6.2.1
Previous Variation Next Rapid Species Change
  • Genetic variation originates from mutations.
  • A mutation is a change in the DNA sequence.
  • Mutations can have no effect, some effect, or a large effect on an organism's phenotype.
  • Phenotype refers to the physical characteristics of an organism.
  • Mutations occur during the process of cell division, specifically when DNA is being copied.
  • In multicellular organisms, mutations in the zygote (fertilized egg cell) can affect every cell in the offspring.
  • Most mutations do not affect the phenotype, meaning the organism appears unchanged despite the mutation.
  • Some mutations can influence traits, such as slightly altering hair color.
  • Most traits are influenced by multiple genes, so a single gene mutation usually has a minor effect.
  • Very few mutations completely determine a phenotype due to the rarity of traits coded by a single gene.
  • An example of a trait determined by a single gene is blood group, where one mutation can change the entire blood group.

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