Test Crosses in Genetics

• ↑

  • Genetics

• Test Crosses in Genetics

  • Where we find out what the genotype of a parent is by breeding with a homozygous recessive parent.
  • Breed someone with a homozygous recessive individual.
  • Find the offspring and find out what the genotype of someone is.
  • Cross between someone of unknown genotype, with someone who is homozygous with recessive genes for that trait. Finding the phenotype of offspring would tell us the genotype.

    • What is a test cross? ;; Breeding an unknown genotype organism with a known homozygous recessive organism to figure out what the genotype is.

    • How do you know what the genotype of an unknown organism is with a test cross? ;; By analyzing the phenotype of the offspring of the two parents. If we know one is homozygous recessive, and the offspring produces any recessive offspring, the unknown parent must have at least one recessive gene

    • Homozygous recessive only has genes for one trait.

    • Ex:

      • Mother has Bb
      • Father has bb
      • Offspring has bb and Bb
      • We would then know what the mother has. Because the only way bb can come out, is with a recessive gene.