How is sex-linked inheritance different from autosomal inheritance?

Sex-linked inheritance involves genes located on sex chromosomes, while autosomal inheritance involves genes on non-sex chromosomes.

Sex-linked inheritance and autosomal inheritance are two different types of genetic inheritance. The key difference between them lies in the location of the genes involved. In sex-linked inheritance, the genes are located on the sex chromosomes, which are the X and Y chromosomes in humans. On the other hand, in autosomal inheritance, the genes are located on the autosomes, which are the non-sex chromosomes.

In humans, there are 23 pairs of chromosomes, 22 of which are autosomes and one pair is sex chromosomes. Males have one X and one Y chromosome (XY), while females have two X chromosomes (XX). This difference in sex chromosomes between males and females leads to unique patterns of inheritance for sex-linked traits. For instance, a male inherits his X chromosome from his mother and his Y chromosome from his father. Therefore, if a trait is X-linked, a male only has one copy of the gene and will express the trait if he inherits the recessive allele from his mother. In contrast, a female has two X chromosomes and would need to inherit two copies of the recessive allele to express the trait.

Autosomal inheritance, however, does not depend on the sex of the individual. Both males and females have two copies of each autosome, so they have two copies of each autosomal gene. Autosomal traits follow the principles of Mendelian inheritance, where dominant alleles mask the expression of recessive alleles. Therefore, an individual will only express an autosomal recessive trait if they inherit two copies of the recessive allele, regardless of their sex.

IB Biology Tutor Summary: In simple terms, sex-linked inheritance deals with genes on the X and Y chromosomes, affecting traits differently in males and females. Autosomal inheritance involves genes on the 22 other chromosome pairs, unrelated to the individual's sex. While sex-linked traits depend on a single gene from a parent, autosomal traits require two copies of a gene to be expressed, following basic Mendelian rules.