Question

can two parents with normal vision have a colorblind son? show your work.

• use the punnett square to determine whether a colorblind son is possible.

yes

Explanation:

Step1: Determine the genotypes

Color - blindness is an X - linked recessive disorder. Let \(X^B\) represent the normal allele and \(X^b\) represent the color - blind allele. Males have the genotype \(XY\). Since the father has normal vision, his genotype is \(X^BY\). Females have the genotype \(XX\). For a female with normal vision to be a carrier (able to pass on the color - blind allele), her genotype is \(X^BX^b\).

Step2: Set up the Punnett square

The father (\(X^BY\)) can produce two types of gametes: \(X^B\) and \(Y\). The mother (\(X^BX^b\)) can produce two types of gametes: \(X^B\) and \(X^b\).

	\(X^B\) (from mother)	\(X^b\) (from mother)
\(Y\) (from father)	\(X^BY\) (normal male)	\(X^bY\) (color - blind male)

Answer:

Yes, two parents with normal vision (father: \(X^BY\), mother: \(X^BX^b\)) can have a color - blind son (\(X^bY\)) as shown in the Punnett square above.