Skip Navigation
Genetics Home Reference: your guide to understanding genetic conditions About   Site Map   Contact Us
 
Home A service of the U.S. National Library of Medicine®

How many chromosomes do people have?

Previous page Next page Previous page Next page

In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46. Twenty-two of these pairs, called autosomes, look the same in both males and females. The 23rd pair, the sex chromosomes, differ between males and females. Females have two copies of the X chromosome, while males have one X and one Y chromosome.

The 22 autosomes are numbered by size. The other two chromosomes, X and Y, are the sex chromosomes. This picture of the human chromosomes lined up in pairs is called a karyotype.

The 22 autosomes are numbered by size. The other two chromosomes, X and Y, are the sex chromosomes. This picture of the human chromosomes lined up in pairs is called a karyotype.

For more information about the 23 pairs of human chromosomes:

Genetics Home Reference provides information about each human chromosome written in lay language.

The University of Utah’s Genetic Science Learning Center discusses how karyotypes can be used in diagnosing genetic disordersThis link leads to a site outside Genetics Home Reference..

Arizona State University’s “Ask a Biologist” discusses the inheritance of human chromosomes.This link leads to a site outside Genetics Home Reference.


Next: How Genes Work

 
Published: September 8, 2014