Final answer:
The X chromosome has approximately 2,000 genes, and the Y chromosome has fewer than 100 genes. Three genetic conditions linked to the X chromosome are hemophilia, Duchenne muscular dystrophy, and color vision deficiency. The presence of two X chromosomes in females offers a protective effect against X-linked disorders.
Step-by-step explanation:
How Many Genes Are on the X and Y Chromosomes?
The X chromosome contains approximately 2,000 genes, while the Y chromosome has fewer than 100 genes. Many genes on the X chromosome are unrelated to sex whereas the Y chromosome is essential for determining male sex, with the crucial SRY gene triggering male development.
Genetic Conditions Linked to the X Chromosome
Several genetic conditions are linked to the X chromosome. These include:
- Hemophilia: A disorder affecting blood clotting.
- Duchenne muscular dystrophy: A condition characterized by progressive muscle degeneration and weakness.
- Color vision deficiency: Commonly referred to as color blindness, this condition affects an individual's ability to distinguish certain colors.
In females, the presence of two X chromosomes (XX) allows for a compensatory effect if one X chromosome carries a defective gene. However, males, having only one X chromosome (XY), will express the condition if the single X chromosome has a defective gene related to such conditions.