DNA

DNA 1 Deoxyribonucleic acid, one of the two molecules (along with RNA) that encode genetic information. DNA is double-stranded. The two strands are held together by weak hydrogen bonds between base pairs of nucleotides to form a double helix. The double helix looks something like an immensely long ladder twisted into a helix, or coil. The sides of the ladder are formed by a backbone of sugar and phosphate molecules, and the rungs consist of nucleotide bases joined in the middle by the hydrogen bonds. The four nucleotides in DNA contain the bases adenine (A), guanine (G), cytosine (C), and thymine (T). 2 In the UK, an abbreviation for “did not attend,” comparable to the US term “no-show” for a patient who missed an appointment.