How does the inheritance of sex-linked genes differ from autosomal genes?

Sex-linked genes are inherited differently from autosomal genes because they are located on the sex chromosomes, not the autosomes.

Sex-linked genes are found on the sex chromosomes, which in humans are the X and Y chromosomes. The inheritance of these genes differs from autosomal genes, which are located on any of the other 22 pairs of chromosomes, known as autosomes. The key difference lies in how these genes are passed on from parents to offspring.

In humans, females have two X chromosomes (XX) and males have one X and one Y chromosome (XY). This means that a male inherits his X chromosome from his mother and his Y chromosome from his father, while a female inherits one X chromosome from each parent. Therefore, a male only has one copy of each X-linked gene, while a female has two. This is why males are more likely to express a recessive trait carried on the X chromosome, as they do not have a second X chromosome to potentially carry a dominant allele that could mask the expression of the recessive one.

For example, colour blindness is a common X-linked recessive trait. A male only needs to inherit one recessive allele from his mother to be colour blind, while a female would need to inherit two recessive alleles, one from each parent, to express the trait. This is why colour blindness is more common in males than females.

On the other hand, autosomal genes are inherited in a more straightforward manner. Each parent contributes one allele for each autosomal gene, and the combination of these two alleles determines the offspring's genotype and phenotype for that trait. This applies equally to both males and females, as autosomes are not involved in determining sex.

In summary, the inheritance of sex-linked genes is influenced by the sex of the individual, as these genes are located on the sex chromosomes. This is different from autosomal genes, which are inherited independently of the individual's sex.