Females (XX) carry twice as many X-linked genes on their sex chromosomes as males (XY). How do cells control gene expression to manage this potentially lethal dosage problem? A prime example of X ...

A young boy fell so deeply in love after seeing his ... which occurs when an individual is born with an extra copy of chromosome 21, according to the Centers for Disease Control and Prevention.

Mixed-gender twins are the most common type of fraternals, some 50 percent are boy-girl. To understand this combination: Males have XY chromosomes, females have XX chromosomes. You have a girl ...

Why are the human sex chromosomes called “X” and “Y,” while the other 22 chromosomes are identified only by numbers? The answer begins in the late 1800s, when insect gonad cells, whose large ...

The genetic information within each of these daughter cells is identical. A human cell contains 46 chromosomes. To simplify our illustration, we'll show only four. Though the genetic code of a ...

Imagine you look in mom’s cell-free DNA and you find a bunch of Y chromosomes. The baby will be a boy, right? If you don’t see any Y chromosomes, a girl. Similarly, a fetus with Down Syndrome ...

A chromosome is a single, long molecule of DNA. These highly organized structures store genetic information in living organisms. Small sections of the chromosome, called genes, code for the RNA ...