Why did it take until 1956 to figure out the correct human chromosome number, thanks to Joe Hin Tjio and Albert Levan? Aa Aa Aa The rediscovery of Mendel's laws near the beginning of the twentieth ...

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 ... In 1891, German biologist Hermann Henking counted 11 ...

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 ...