Each of the 23 DNA molecules that make up the human genome, which is the genetic code found in every human cell, has between 500 000 and 2.5 million nucleotide pairs. When uncoiled, these DNA molecules range in length from 1.7 to 8.5 cm, or on average 5 cm. The human body contains around 37 trillion cells, and if you were to uncoil all of the DNA that is wrapped up inside each one and lay it end to end, it would total 21014 metres, or enough to make 17 journeys around Pluto.