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In humans, oculocutaneous (OCA) albinism is a collection of autosomal recessive disorders characterized by an absence of the pigment melanin in skin, hair, and eyes. That is, normal pigmentation ( A ) is dominant over albino characteristics.
For this question, assume the phenotype is determined by a single gene with two alleles. If two people have normal pigmentation, what possible phenotypes may be observed in their offspring?

Respuesta :

The offspring may have: normal pigmentation or may have albinism.

Explanation:

  • If the person has normal pigmentation, then his possible genotype can be AA or Aa.
  • Since both the parents have normal pigmentation, then there could be three cases of combination,
  • Case 1:  Both the parents have AA genotype.
  • Case 2: One parent is AA and other one is Aa.
  • Case 3 : Both parents are Aa.

In case 1:

AA  x  AA

will produce all offsprings with  genotype AA; normal pigmentation.

In case 2:

AA  x  Aa

has 50% chance of producing offsprings with genotype Aa and 50% chance of producing offsprings with genotype AA. Phenotype of offsprings in both cases will be normal.

In case 3,

Aa x Aa

has 25% chance of producing offsprings with genotype AA, 50 % chance of producing offsprings with genotype Aa and 25% chance of producing aa genotype.

Offspring with genotype AA or Aa will have normal pigmentation and offsprings with genotype aa will be albino.

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