Describe and summarize any similarity of the human X chromos

Describe and summarize any similarity of the human X chromosome with chromosomes of chickens. What do you suggest about the origin of the human X chromosome?

Solution

In humans, females contains, 23 pairs of matched chromosomes (homologous chromosomes), 22 of these are pairs of autosomes (non-sex chromosomes) and one pair of homologues “X” chromosomes. But in males, each cell contains 22 pairs of homologues autosomes and another of one “X” chromosome paired with one “Y” chromosome. So, “Y” chromosome is the sex-determining chromosome in humans.

Birds contain ZW sex determination, the genotype of females is ZW and the genotype of males is ZZ. In birds, sex is determined by the ZW system, ZZ (homogametic) are males, ZW (heterogametic) are females (this is in contrast to human sex determination system).

The ZW and XY sex chromosomes share no genes, they were evolved independently (convergent evolution).