Human DNA facts

DNA Facts: If a chromosome was stretched straight it would be 1.7 to 8.5 cm in length. If the diameter of the DNA (2 nanometers) was as wide as a fishing line (0.5 millimeters) it might stretch as far as 21.2 km (or 13.6 miles) in length which would all have to be packed into a nucleus sack the equivalent of 25 cm in diameter. That is some packaging! The human genome is contained in 23 pairs of chromosomes. The DNA within the human genome makes up 60,000 to 100,000 genes. Human chromosomes vary in size from 50 million to 250 million base pairs (or rungs on the double helix ladder).