Investigate the causes of genetic variation

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Investigate the causes of genetic variation relating to the processes of fertilisation, meiosis and mutation

Causes of genetic variation relating to the processes of fertilization, meiosis and mutation:

  • Fertilization
    • During fertilization, a zygote receives half of the genotype from mother and the other half from the father. Various types of interactions in the genes (dominant, recessive, epistasis etc) can result in production of traits that neither of the parents possessed.
  • Meiosis:
    • One of the principal causes of genetic variation is Crossing Over during meiosis. Crossing over results in exchange of parts between non-sister chromatids, thus, recombination results in genetic variation.
  • Mutations:
    • Exposure to biohazardous chemicals and radiations causes aberrations in genes and chromosomes which can be numerical and structural.
    • The changes cause genetic variation in a number of ways including:
      • Adding or removing parts of gene creates defective protein or might create a less functioning protein with a deviant structure.
      • Silencing genes that can eliminate a particular trait.
      • Adding, deleting, translocating chromosomes causing disorders in organisms, some of which are untreatable and lethal.
      • Mutations can also produce different products from similarly sequenced mRNA transcripts.

Extract from HSC Biology Stage 6 Syllabus. © 2017 Board of Studies NSW.