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How do sex chromosomes differ from autosomes?

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In humans and many other organisms, chromosomes are categorized into two distinct types: autosomes and sex chromosomes.

Autosomes

Autosomes are the nonsex chromosomes that make up the first 22 pairs in human cells. They are numbered based on their size, shape, and other properties. Autosomes are similar in both males and females and control the inheritance of the vast majority of an organism's characteristics, excluding those that are sex-linked. Because they exist in homologous pairs, they provide genetic redundancy, which helps protect the organism from the effects of harmful mutations.123

Sex Chromosomes

Sex chromosomes constitute the 23rd pair of chromosomes. Unlike autosomes, which are generally uniform, sex chromosomes differ between the sexes and are responsible for determining an individual's biological sex. In humans, females typically possess two X chromosomes (XX), while males typically possess one X and one Y chromosome (XY).3214

The Y chromosome is generally smaller than the X chromosome and carries different gene content. While autosomes are always homologous, sex chromosomes may differ in size and composition, yet they still pair during meiosis to ensure proper distribution to reproductive cells.12