Saturday Genetics Quiz #21: The X Chromosome
This week’s genetics quiz questions are about the X chromosome:
1. What is the X chromosome?
2. How many X chromosomes do men and women have?
3. The X chromosome represents what percent of the total DNA in cells?
4. How many genes does the X chromosome have?
5. What are some of the diseases caused by mutations in the X chromosome, either in the structure or number of copies?
Answers:
1. The X chromosome determines a person’s sex. It is one of two sex chromosomes, the other is the Y chromosome.
2. Under normal circumstances, men have one X chromosome and women have two.
3. The X chromosome represents 5 percent of the total DNA in cells.
4. The X chromosome has between 900 and 1,200 genes.
5.
- Klinefelter syndrome – one or more X chromosomes in a male’s cells leading to problems with sexual development, testicular function, and testerone levels.
- Triple X syndrome – Extra copy of the X chromosome in a female’s cells leading to mental retardation and other medical problems.
- Turner syndrome – A condition found in females with one normal and one abnormal X chromosome can lead to short stature and infertility.
