- Sex-linked genes are located on the sex chromosomes.
- X-linked genes can exhibit different patterns of inheritance in males and females.
- Thomas Hunt Morgan conducted important experiments with Drosophila to study sex-linked genes. He observed that certain genes were located on the X chromosome, leading to unique inheritance patterns.
- Morgan carried out dihybrid crosses in Drosophila, similar to Mendel's experiments with peas.
- For example, he hybridised yellow-bodied, white-eyed females (XX) with brown-bodied, red-eyed males (XY).
- When intercrossing their F1 progeny, he noted that the two genes (body colour and eye colour) did not segregate independently as Mendel's 9:3:3:1 ratio would predict.
- This observation indicated that these genes were linked on the same chromosome.
- This phenomenon is essential in understanding the inheritance of traits like colour blindness in humans.