Three copies of chromosome 21 cause Down syndrome (DS), and roughly half of children born each year in the United States with ...

A mixture of DNA and proteins—known as "chromatin"—sits inside every cell nucleus as a jumbled puddle of genetic information. As cells prepare to divide during mitosis, the chromatin is condensed into ...

Scientists have confirmed that the Atlas blue butterfly carries the most chromosomes of any animal, with 229 pairs. Unlike duplication, its chromosomes split apart, reshaping its genome in surprising ...