Mutations occur when DNA molecules are exposed to agents known as mutagens. Mutagens damage DNA in a variety of ways; nucleotide bases are either deleted, added, rearranged or substituted. In almost every case the original sequence of bases is altered. When the DNA message is transcribed into a messenger RNA molecule, the mistakes caused by the mutagen are also copied. The mRNA molecule is now carrying the altered coding sequence. As the mRNA molecule is translated into a polypeptide sequence, any mistakes in the message result in altered amino acid sequences in the final protein.
Mutagenesis affects DNA, but in this exercise you will skip that stage and simply alter the mRNA molecule directly. You will then use the modified mRNA molecule to direct the synthesis of a polypeptide and record the sequence of amino acids that are produced. By comparing the polypeptide sequence before and after mutagenesis you will be able to build a table that shows the various possible effects of various mutations.