The human genome present in the nucleus of nearly all cells within the body is composed of 3.2 billion base pairs. If unwound, this DNA would stretch to about 6 feet.
All cells except red blood cells contain a copy of the human genome within the nucleus. The genome consists of 3.2 billion base pairs, which code for approximately 70,000 genes that instruct the cell to make proteins. Most genetic information, about 98 percent, is known as non-coding DNA and does not code for proteins. DNA is arranged in a helical form that is tightly condensed into chromatin, which is stored within chromosomes. Humans have two copies, one from each parent, of 23 different chromosomes.