Well, as we'll see in a future lecture, it turns out that the sequence of amino acids in a protein actually determines its three dimensional structure. So under the proper cellular conditions, this linear sequence of amino acids can actually fold into its three dimensional structure spontaneously. And once these proteins form their three dimensional conformation, their function is basically determined. 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.