Cambridge Graduates' Science Club

Date:
1962-1963
Reference:
PP/CRI/E/1/11/2
Catalogue details

Licence: In copyright

Credit: Cambridge Graduates' Science Club. Source: Wellcome Collection.

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    The Genetic Code for Prot el ns Proteins consist of polypeptide chains which are formed by joining together amino acids head to tail. A typical chain may he some hundreds of residues long. Only 20 different amino acids are fount! in proteins no matter what the biological origin of the protein. There are two sorts of nucleic acid» DNA and RIA, Each has a regular backbone consisting of an alternating sequence of phos phate and sugar groups. The sugar is ribose in RNA and the closely related deoxyribose in DNA. To each sugar is attached a flat heterocyclic molecule called a base. There are four sorts of bases in both DIA and RNA, In MA they are adenine, guanine, eytosine and thymine. In RNA thymine (which is 5-mthyIuracil) is replaced by uracil. The genes cosist of part of a nucleic acid molecule. It is typically some hundreds of bases long. There is evidence that the amino acid sequence of any protein is determined by its own particular gene. Thus in some way a sequence of four different things (the bases in nucleic acid) determines the sequence of 20 different things (the amino acids in protein). The problem of how this is done is known as the coding problem. There is in all cells an intricate biochemical mechanism for protein synthesis, parts of which are fairly well understood. In