How are proteins created?
The genetic code in DNA (deoxyribonucleic acid) provides the instructions for building proteins. In the 1960s, Marshal Nirenberg at the National Institutes of Health (NIH) deduced how DNA is mapped into proteins. DNA consists of long molecular sequences containing four nucleotide bases: Adenine (A), Cytosine (C), Guanine (G), and Thymine (T). Each combination of three bases, a DNA codon, corresponds to one specific amino acid. Since there are 64 different 3-base combinations and only 20 amino acids, some combinations do not have unique mappings. The genetic code applies to the vast majority of genes in animals, plants, and microorganisms. The same codons correspond to the same amino acids and to the same START and STOP signals, but in some rare cases one or two of the three STOP codons are assigned to an amino acid instead.
