In a case of disputed paternity, the child is type O and the mother is type A. Could an individual of the following blood types be the father? Explain each possibility.

O

A

B

AB

Please answer please please

The only possibility for a person to be 0 blood type -ii- is that both parents are carriers of the recessive allele. The possible father of this child could be either blood type A, blood type B, or blood type 0. Options 1, 2, and 3.

The I diallelic gene determines the blood type of a person. I allele is dominant over the recessive i allele.

⇒ H0m0zyg0us dominant individuals IAIA, or heter0zyg0us Individuals IAi, will express the A blood type.

⇒ H0m0zyg0us dominant individuals IBIB, or heter0zyg0us Individuals IBi, will express the B blood type

⇒ Individuals with h0m0zyg0us recessive genotype, ii will express the 0 blood type.

⇒ Individuals carrying IA and IB alleles will express the AB blood type.

Knowing this, we can answer the question.

Available data:

The mother must be heter0zyg0us fror blood type A, because her child received a recessive allele i from each parent. So she must be IAi.

The father provided another i recessive allele to the child. There are many possible genotypes for the father:

An individual expressing any of these genotypes could provide a recessive allele i to the child.

The only option that can be automatically rejected is blood type AB, because an individual with this genotype could only provide either IA allele or IB allele.

The child could never inherit a i allele from this person.

Could an individual of the following blood types be the father?

Yes, Individuals with blood type A, B and 0 could be the father. Any of them could provide a recessive allele.

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Explanation:

For someone to be type O, that person must have 2 recessive traits for blood type. Let's denote this using the lowercase letter "i," thus making someone with blood type O "ii."

Next the mother is type A. The mother can either be homozygous for the dominant blood type A allele or heterozygous for the trait. This means either of the two following genotypes: AA, or Ai. However, if her child is type O, that means that the mother must have at least one recessive allele, meaning her genotype is "Ai."

Now, let's go to the father. Let's find out his genotype. Start with blood type O. Yes, this works, because the father can donate a recessive allele for blood type to his child. Next, blood type A, which as stated above can be represented by the genotype "Ai" or "AA."  Can Ai work? Yes! So we know that an individual of blood type A can be the father. Same goes for blood type B, as someone with that blood type can be heterozygous for it... IE Bi. Next, blood type AB. This DOES NOT work. Why? Because there is no recessive allele for the father to donate to the child. Therefore, the only blood types that the father can have are O, A, and B.

Conclusion:

Hope you found this helpful. It certainly helped me review :)

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