So it turns out, as we'll see in a future lecture, that the three dimensional structure of the protein determines its actual function. Now, the next question is, what exactly is the difference between one amino acid and another amino acid? Well, basically, amino acids differ from one another based on the side chain group, the functional group that exists on that amino acid. For example, we have one type of amino acid known as glycine, and this contains an age group, while another amino acid contains this side chain group that is known as cysteine. And these two amino acids have different functionalities. For example, cysteine is important in forming these linkages known as disulfide bridges.