Question

charles
marie
fred
jack
irene
x^h y
x^h x^h
?
x^h y
?
?
in the pedigree that is shown, which represents irenes allele combination?
x^h x^h
x^h x^h
x^h x^h
x^h y

Explanation:

• In genetics, females have two X chromosomes (\(XX\)), and males have \(XY\). Since Irene is female (represented by a circle), we can eliminate \(X^{h}Y\) (which is male).
• Her father has \(X^{H}Y\), so he must pass on an \(X^{H}\) to his daughter (Irene).
• Her mother has \(X^{H}X^{h}\). But Irene is not shaded (assuming shaded represents having a recessive - related trait). If the trait is recessive (assuming \(h\) is recessive), to not show the recessive trait, she cannot have \(X^{h}X^{h}\). Also, since she gets one \(X\) from her father (\(X^{H}\)) and if she is non - affected (assuming the normal allele is \(H\)), and considering the non - shaded circle (female), she must have \(X^{H}X^{H}\).

Answer:

\(X^{H}X^{H}\)