Study the pedigree chart of a certain family | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(C) The pedigree shows an affected father and an unaffected mother producing both affected and unaffected offspring. This pattern is consistent with a

Vedclass · Accepted Answer

The trait under study could not be colour blindness.

Vedclass · Answer

(C) The pedigree shows an affected father and an unaffected mother producing both affected and unaffected offspring. This pattern is consistent with an autosomal dominant trait. Let the dominant allele be $A$ and the recessive allele be $a$. The affected father must be heterozygous $(Aa)$ because he has an unaffected son $(aa)$. The unaffected mother must be homozygous recessive $(aa)$. The cross is $Aa 	imes aa$. The offspring genotypes are $Aa$ (affected) and $aa$ (unaffected). Since the mother is $aa$,she contributes an $a$ allele to all children. The father contributes either $A$ or $a$. Therefore,the female parent is homozygous recessive $(aa)$,and the male parent is heterozygous $(Aa)$. Option $(A)$ is incorrect because the female parent is homozygous recessive. Option $(B)$ is incorrect because they can have a normal daughter $(aa)$. Option $(C)$ is correct because if the trait were colour blindness ($X$-linked recessive),an affected father would pass the trait to all his daughters,but here he has an unaffected daughter (if we assume the circle represents a daughter,though the pedigree shows two affected daughters and one unaffected son and one affected son). Actually,looking at the pedigree,the father is affected and the mother is unaffected. They have two affected daughters,one unaffected son,and one affected son. This is consistent with an autosomal dominant trait. If it were $X$-linked recessive,an affected father $(X^aY)$ and normal mother $(X^AX^A)$ would produce normal daughters $(X^AX^a)$ and normal sons $(X^AY)$. Thus,it cannot be $X$-linked recessive (colour blindness).

Study the pedigree chart of a certain family given below and select the correct conclusion which can be drawn for the character.

Similar Questions

The harmful allele of sickle cell anemia has not been eliminated from the human population. Such afflicted people derive some other benefit. Discuss.

Mendelian disorders may be of which type?

If a normal woman marries a colourblind man,what will be the phenotype of their children?

Which one of the following disorders and its characteristic is correctly matched?

Select the correct trait from the given pedigree chart.

Vedclass Test Series

Exam Paper Generator

Online Exam Module