Biochemistry: The Chemical Reactions of Living Cells, Volume 1 - D. Metzler 1980
Setting the Stage
Evolution of Complex Organisms
Sex Chromosomes and Autosomes
The diploid Cells of most higher organisms contain a single pair of Chromosomes that, among other things, determine the sex of the individual. In females, cells contain a pair of X chromosomes, whereas in males they contain one X chromosome and a paired, truncated Y chromosome1.
Genes located on the sex chromosomes are said to be sex-linked. Because the majority of such genes are localized on the longer X chromosome rather than the Y chromosome, genetic defects manifest much more frequently in males, who possess only a single copy of these genes, than in females. For instance, hemophilia and color blindness predominantly affect males. In most cases, females are heterozygous for the defective Gene, meaning they carry a normal allele on their second X chromosome2.
Furthermore, if only one gene in the pair is damaged (as is typically the case), the individual remains virtually healthy. In this scenario, the defective genetic trait is referred to as recessive. For example, both hemophilia and color blindness are sex-linked and recessive traits.
All chromosomes other than sex chromosomes are referred to as autosomes, and the genes located on them as autosomal.
Last update: 06/08/2026
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