If a father is affected by an X-linked dominant condition and the mother is not, which children can inherit the condition? only males
neither males nor females
only females
O both males and females

only females

Explanation:

In humans, sex chromosomes in males and females are different. The sex chromosomes found in humans are X and Y chromosomes. X-linked trait is a trait which is inherited on the X- chromosome. According to the question, the trait is passed on a X-linked dominant condition, which means the condition is inherited on the abnormal dominant X-chromosome that will express itself even when in an heterozygous state with a normal X-chromosome.

Hence, a father affected by the condition will have a genotype; XY while a mother that does not have the condition will have a genotype: xx (two normal x chromosomes). Since the Father can only pass his X chromosome to his daughters and never his sons, all his daughters will inherit the condition (see the punnet square in attached image).

N.B: None of the sons will inherit the condition since the mother will pass normal X-chromosomes (x) to her sons.

an individual’s sex (i.e., whether they are a male or female) is determined by the sex chromosomes. most people have two sex chromosomes, one that is inherited from their mother and one that is inherited from their father. typically, females have two x chromosomes (xx) and males have one x chromosome and one y chromosome (xy). conditions caused by changes (“mutations”) in genes located on the x chromosome are considered x-linked.

x-linked recessive inheritance

most x-linked conditions are recessive. this means that in a person with two x chromosomes (most females), both copies of a gene (i.e., one on each x chromosome) must have a change or mutation whereas in a person with one x chromosome (most males), only one copy of a gene must have a mutation. a female with a mutation in one copy of a gene on the x chromosome is said to be a “carrier” for an x-linked condition. a male with a mutation in a gene on the x chromosome is typically affected with the condition. because females have two copies of the x chromosome and males have only one x chromosome, x-linked recessive diseases are more common among males than females. however, x-linked recessive diseases can occur in both males and females.

for x-linked recessive disorders, an unaffected carrier mother who has a mutation in a gene on the x chromosome can transmit either the x chromosome with this mutation or a “normal” x chromosome to her children. if the father is unaffected, none of her daughters will be affected and all of her daughters will be unaffected—since they will inherit at least one normal x chromosome from their father. however, each daughter will have a 50% chance of being an unaffected carrier like her mother and a 50% chance of both x chromosomes being normal.