Question

Mr.Sharma has Bb autosomal gene pair and d allele sex-linked.What will be the proportion of Bd in sperms?
A. 0
B. $\dfrac{1}{2}$
C. $\dfrac{1}{4}$
D. $\dfrac{1}{8}$

Answer 1

Hint: Two alleles present in all genes. Alleles are dominant or recessive at all times.
There is a different set of alleles for each organism of a species from any other member of that species. Alleles are different variants of a given gene. Alleles are inherited only from the mother.

Complete Answer:
A feature in which a gene is located on a sex chromosome is sex-linked. In humans, the term usually refers to characteristics on the X chromosome that are affected by chromosomes. This is because the X chromosome is bigger than the smaller Y chromosome and contains far more genes. In a sex-linked disorder, since they have a single copy of the X chromosome bearing the mutation, it is usually males that are affected. In females, the second healthy copy of the X chromosome can mask the impact of the mutation.

An autosome is any numbered chromosomes, as opposed to sex chromosomes. There are 22 pairs of autosomes and one pair (the X and Y) of sex chromosomes in humans. The autosomes are approximately numbered in relation to their proportions. That is, there are approximately 2,800 genes in Chromosome 1, while chromosome 22 has approximately 750 genes.

Since d is sex-linked, BbdY is going to be the genotype of Mr. Sharma.

	B	b
d	Bd	bd
Y	BY	bY

The alleles would, therefore, be:
Bd-at 25% ($\dfrac{1}{4}$)
bd-25% ($\dfrac{1}{4}$)
BY-25% of ($\dfrac{1}{4}$)
bY - 25% ($\dfrac{1}{4}$)

Thus the correct answer is option(C) $\dfrac{1}{4}$.

Note: An autosome is any chromosome that is not a sex chromosome (an allosome). The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosome pairs that may have different structures. DNA in autosomes is generally known as atDNA or auDNA.