| A | B |
| amino acid | building block of protein |
| peptide bond | bond between amino acid groups |
| protease | protein enzyme |
| pepsin | protein enzyme in the stomach |
| substrate | chemical an enzyme acts upon |
| enzyme | protein that speeds up a reaction |
| denature | permanently alters an enzyme |
| xanthoproteic | test for proteins - turns them yellow |
| R group | the part of an amino acid that changes |