Just show how changes in DNA can ultimately produce either:
- different proteins because different amino acids are chained together in a polypeptide chain, therefore changes intended cell activity.
- the same proteins (remember, there usually are several equivalent triplet sequences to code for the same amino acid), and hence no unintended changes to cell activity.
- useless proteins (polypeptide chains failing to combine together into a three dimensional shape because of a changed polypeptide chain), therefore no changes to cell activity.