Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
The X chromosome is one of the two sex chromosomes in humans (the other being Y). Females have two X chromosomes while males have one X and one Y chromosome.
Related terms
Sex-linked Traits: These are traits associated with genes found on sex chromosomes.
Autosomes: These are all other chromosomes that aren't involved in determining sex; humans have 22 pairs.
Hemizygous Trait: A trait where only one allele is present because it occurs on the single X-chromosome in males.