Introduction to Genetic Variation

• Genetic Variation


  • the difference in the DNA sequence of each of our genomes (our entire genetic make up)
  • it's what makes each of us unique from each other, whether it is our hair colour, eye colour, height, or even our fingerprints.

  
  

  NOTE: Don't just say that genetic variation is the differences between individuals from the same species. This is only variation, NOT genetic variation. You must include that it is the differences in the DNA sequence.
• Sources of Variation


  There are four main sources of genetic variation:

  1. Mutation
  2. Sexual reproduction through meiosis
  3. Fertilisation
  4. Environment
• Mutations as a Source of Variation


  • is a permanent change in the base sequence of DNA which may result in a new allele being formed, increasing genetic variation.
  • it can occur naturally during DNA replication, or may occur as a result of exposure to mutagens.
  • mutations can only be passed on if it occurs in the gametes. It will not be passed on if it occurs in the somatic cells (body cells).
• Mutations as a Source of Variation

  It can be:

  1. silent/neutral - they have no effect on the organism
  2. harmful - which may impact the organism’s survival chances.
  3. beneficial - occasionally, a beneficial mutation will give the organism a survival advantage.