Question

multiple alleles day 15
some traits are controlled by more than two alleles, which means there are multiple versions of a gene in a population. this is called multiple alleles. human blood type is an example. there are three alleles: a, b, and o.

• a and b are codominant, meaning both can be expressed together.
• o is recessive, meaning it only shows when both alleles are o.

1. write the possible genotypes for each blood type (a, b, ab, and o).
2. if one parent has type a (ao) and the other has type b (bo), complete a punnett square to show the possible blood types of their children.

Explanation:

1.

• For blood type A: Since O is recessive, genotypes can be AA (both alleles A) or AO (one A and one recessive O).
• For blood type B: Similarly, genotypes can be BB (both alleles B) or BO (one B and one recessive O).
• For blood type AB: As A and B are codominant, the only genotype is AB.
• For blood type O: Because O is recessive, it requires both alleles to be O, so the genotype is OO.

Step1: Set up the Punnett square

Parents have genotypes \(AO\) (type A) and \(BO\) (type B). The possible gametes from parent with \(AO\) are \(A\) and \(O\). The possible gametes from parent with \(BO\) are \(B\) and \(O\).

	\(A\)	\(O\)
\(O\)	\(AO\)	\(OO\)

Step2: Determine the blood types

• \(AB\) corresponds to blood type AB (A and B codominant).
• \(BO\) corresponds to blood type B (B dominant over O).
• \(AO\) corresponds to blood type A (A dominant over O).
• \(OO\) corresponds to blood type O (both O alleles).

Answer:

• Blood type A: \(AA\), \(AO\)
• Blood type B: \(BB\), \(BO\)
• Blood type AB: \(AB\)
• Blood type O: \(OO\)

2.