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Flower color in the garden pea is due to two interacting genes, A and B. If either gene is recessive (aaB_, A_bb, or aabb) then the phenotype is white. A dominant allele must be present at both genes for flower color to be purple. After a testcross of an individual with a genotype of AaBb, what proportion of the progeny will have purple flowers

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marianaegarciaperedo

Answer:

4/16 = 1/4 = 25% of the progeny is expected to be purple (AaBb)

Explanation:

Available data:

  • Flower color in the garden pea is due to two interacting genes, A and B
  • aaB_, A_bb, or aabb ⇒ white flower
  • A dominant allele must be present at both genes for flower color to be purple
  • AABB, AaBb ⇒ purple flower

Cross:

Parentals) AaBb    x     aabb

Gametes) AB, Ab, aB, ab

                ab, ab, ab, ab

Punnett square)      AB         Ab       aB        ab

                  ab       AaBb    Aabb    aaBb   aabb

                  ab       AaBb    Aabb    aaBb   aabb

                  ab       AaBb    Aabb    aaBb   aabb

                  ab       AaBb    Aabb    aaBb   aabb

F1) Genotype:

  • 4/16 = 1/4 = 25% of the porgeny is exected to be AaBb
  • 4/16 = 1/4 = 25% of the porgeny is exected to be Aabb
  • 4/16 = 1/4 = 25% of the porgeny is exected to be aaBb
  • 4/16 = 1/4 = 25% of the porgeny is exected to be aabb

    Phenotype

  • 12/16 = 3/4 = 75% of the progeny is expected to be white(Aabb + aaBb + aabb)
  • 4/16 = 1/4 = 25% of the progeny is expected to be purple (AaBb)

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