And usually proteins consist of hundreds and sometimes thousands of amino acids. And that means there is a great number of different types of sequences that are possible inside the proteins found inside our body. Now, what's so special about this sequence of amino acids? 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.