Chromosomes: Definition, Structure & Function Home / Health Library / Body Systems & Organs / Chromosomes Advertisement Advertisement Chromosomes Medically Reviewed. Last updated on 07/09/2025 . Chromosomes are long strings of DNA wrapped around proteins to make them compact. They’re a way for cells to organize and store your DNA. Humans typically have 23 pairs of chromosomes for a total of 46 chromosomes. The first 22 are called autosomes and the last pair are sex chromosomes. Advertisement Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy Care at Cleveland Clinic Schedule Genetic Counseling Find a Doctor and Specialists Make an Appointment Contents Overview Function Anatomy Conditions and Disorders Overview Image content: This image is available to view online. View image online ( https://my.clevelandclinic.org/-/scassets/images/org/health/articles/chromosomes-illustration ) Chromosomes organize and store your DNA. They come in pairs — 22 pairs of autosomes and one pair of sex chromosomes. What are chromosomes? Chromosomes are long strings of DNA (instructions that make your body work), wrapped around special proteins (histones) to make them compact enough to fit into the nucleus of your cells. Your chromosomes are like individual books in your DNA library. Every one of your cells, except red blood cells and platelets , carries copies of your chromosomes. Advertisement Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy Like socks or gloves, your chromosomes come in pairs. Humans typically have 23 pairs of chromosomes, for a total of 46 chromosomes. Pairs 1 through 22 are called autosomes. The last pair is called sex chromosomes. Autosomes Typically, people have two copies of chromosomes 1 through 22 (autosomes) — yo