What are Chromosomes?

Our bodies are made up of billions of cells.  Within these cells are structures called chromosomes. There are a total of 46 chromosomes, numbered and arranged in 23 pairs. The last pair consists of the sex determining chromosomes.  Females have two X chromosomes and males have an X and a Y chromosome. 

Each chromosome can be divided into several parts.  A special structure called the centromere divides the chromosome into 2 unequal halves, the short arm (p arm) and the long arm, (q arm).  Based on special staining patterns each chromosome arm can be divided into individual sections called bands.  Each band is given a number designating its location along the chromosome arm.

Genes are the very small components of the chromosomes that determine inherited features such as hair, eye, and skin color.  In addition genes provide the very important instructions for how we grow and develop. 

The telomeres are special structures that cap and protect the very ends of each chromosome arm.   The area next to each telomere may contain these important genes for growth and development.