Females, on average, tend to have more genes due to the presence of two X chromosomes compared to males, who have one X and one Y chromosome.
The difference in gene count stems from the sex chromosomes. Humans typically have 23 pairs of chromosomes, with one pair determining sex. Females possess two X chromosomes (XX), while males have one X and one Y chromosome (XY).
-
X Chromosome: The X chromosome is significantly larger and contains far more genes than the Y chromosome.
-
Y Chromosome: The Y chromosome is smaller and carries fewer genes, primarily related to male sexual development.
Because females have two X chromosomes, they inherently have the potential for a larger number of genes actively expressed, compared to males with only one X chromosome. The reference highlights this by stating that the X chromosome is five times larger than the Y chromosome and contains 10 times the number of genes. While one X chromosome undergoes X-inactivation (a process where one X chromosome is silenced in each female cell), there are still some genes on the inactivated X chromosome that remain active and contribute to overall gene expression.
