What are gender-linked traits

Meinstein

Certain traits are gender-linked

White eyes mutant

Discovered in 1912 Bridges, an employee of Morgan, a white-eyed Drosophila mutant. Crossing attempts with these white-eyed animals produced strange results.

female

x

male

If you cross a white-eyed female with a wild male, the F1 generation is not uniform! Are in the F1 generation all females red-eyed and all males white-eyed.
According to Mendel's rule of uniformity, all animals should be red-eyed.

The gene is on the X sex chromosome

The gene for the white eye color must be on the X chromosome and be recessive. In the F1 generation, this is fully expressed in males because they lack a second X chromosome.

If you cross such red-eyed F1 females with white-eyed males, you get white-eyed females and males as well as red-eyed females and males in the F2 generation.

The following diagram of the chromosomes illustrates this.

Sex chromosomes x and y

If one compares the chromosomes of males and females in Drosophila (and also in humans), one finds that, in addition to the three chromosomes occurring in pairs, one does not appear in pairs in males. The fourth pair of chromosomes consists of a rod-shaped X chromosome and a hook-shaped Y chromosome. In females, one of the pairs of chromosomes corresponds exactly to the X chromosome in males.

X and Y chromosomes are called Sex chromosomesbecause with them the determination of sex is connected. The remaining chromosomes are called Autosomes designated. So males in Drosophila (and also in humans) have XY combination, females XX combination of the sex chromosomes.

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