DNA carries the genetic information in the cells of all living organisms. Genes contain codes for the assembly of amino acids into all the proteins required in the body.
The nucleus of each human body cell contains 46 chromosomes. Each chromosome contains about 1000 genes. There is enough DNA in all the cells in a human body to stretch to the sun and back again over 60 times.
Humans inherit 23 of their chromosomes from their mother and 23 chromosomes from their father. Other mammals also inherit half their chromosomes from each parent.