Explain how a change in an allele can stop a protein functioning correctly. (4)

If there is a change in the allele, there will be a change in base sequence of DNA (1) This means there is a change in order of amino acids (1) Therefore the protein shape changes (1) Hence, the protein may not be able to carry out its normal function, for example, if the substrate of the enzyme changes shape it will not be able to fit into the active site any more (1)