DNA molecule. Computer artwork of the molecular structure of a DNA (deoxyribonucleic acid) double helix. DNA carries the genetic code,unique for every individual,that controls the growth and functioning of every living organism. The helix is composed of two twisting sugar-phosphate strands (orange),linked on the inside of the helix by complementary pairs of nucleotide bases (white vertical bars). There are four nucleotide bases: adenine,guanine,cytosine and thymine. It is the sequence of base pairs,arranged in discrete segments known as genes,that determines the genetic code |