A gene is a length of DNA that codes for a single polypeptide chain. When a cell needs a particular protein, the gene for this protein is copied into a complementary RNA molecule (called messenger RNA or mRNA). In some types of cells, this mRNA molecule is processed in various ways before moving to the cytoplasm where it acts as the template for the synthesis of a polypeptide chain. The order or sequence of the bases along the mRNA molecule determines two things; which amino acids are placed into the polypeptide chain and the positions at which these amino acids appear in the polypeptide chain.
During early research, it was shown that a set of three mRNA bases (a triplet, or codon) acted as a 'code word' for each amino acid. In order to 'break' this 'genetic code', scientists artificially synthesized short lengths of RNA with a known order of nucleotide bases. These were then placed in tubes of cell extract and allowed to direct the synthesis of polypeptide chains. From the type and nature of the polypeptides that were made this way, it was possible to work out which codons of bases coded for which sequences of amino acids. The genetic code was broken.
In this simulation you are going to repeat part of this important research and re-break the genetic code for yourself.