Happy Mother's Day from NHGRI
Facts about the X Chromosome that all mothers - all females - carry!
From NHGRI to you: Have a happy Mother's Day and learn about the X chromosome - the chromosome that determines your sex, gives some females super color vision and lends its magic to a certain breed of cat!
10 Neat Facts About the X Chromosome:
- There are two sex-determining chromosomes in humans - the X chromosome and the Y chromosome. Their shape actually looks like X and Y letters in the alphabet.
- Males have one X chromosome and one Y chromosome (It's a boy!), and females have two X chromosome (It's girl!).
- Men always inherit their X chromosome from their mothers.
- Women always inherit one X chromosome from their mother and the other from their father.
- The X chromosome is about 5 times larger than the Y chromosome.
- The X chromosome has about 1,000 genes, 10 times the number of genes in the Y chromosome.
- The XY sex determination system is found in humans, most other mammals, some insects, and some plants.
- Female mammals have two X chromosomes in every cell. But, one of the X chromosomes is "silenced" preventing a "double dose" of genetic information to the X chromsomes.
- Some women have super color vision trait called tetrachromacy, which is linked to the X chromosome. These super women can see up to 100 million shades of color because they have four types of cone cells in their eye instead of the usual three.
- Calico cat is not a breed but a distinctive coat color pattern linked to the X chromsome. Over 95 percent of calico cats are females (XX).
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Last Updated: June 19, 2015