gen-define-sex-linked-inheritance-and-give-one-short-worked-exam-8949

Define sex-linked inheritance and give one short worked example.

# Sex-Linked Inheritance **Definition:** Sex-linked inheritance refers to the inheritance pattern of genes located on the sex chromosomes (X or Y). Most sex-linked traits are **X-linked** because the X chromosome carries many more genes than the Y chromosome. Males (XY) are more frequently affected by X-linked recessive conditions because they have only one X chromosome—if it carries the recessive allele, there's no second X to mask it. ## Worked Example: Color Blindness **Cross:** A woman who is a carrier for red-green color blindness (X^C X^c) has children with a man with normal vision (X^C Y) **Key:** - X^C = normal vision (dominant) - X^c = color blindness (recessive) **Punnett Square:** | | X^C | Y | |---|---|---| | **X^C** | X^C X^C | X^C Y | | **X^c** | X^C X^c | X^c Y | **Results:** - 25% X^C X^C (normal vision daughter) - 25% X^C X^c (carrier daughter) - 25% X^C Y (normal vision son) - 25% X^c Y (color blind son) **Conclusion:** 50% of sons will be color blind, while all daughters will have normal vision (though 50% will be carriers). This demonstrates the characteristic pattern where males are disproportionately affected by X-linked recessive traits.