Now, the final thing that I'd like to mention about amino acids is so amino acids essentially are the same on this group, on this group, and on this group. Now, where we can differentiate one amino acid from another is by the R group, by that side chain. So we have different types of side chains. And these different types of side chains basically determine the type of amino acid that we are discussing. Now, these side chains can basically differ based on their size, based on their shade, based on their structure. They can differ based on the amount of charge found on that side chain, based on the polarity, based on the hydrophobic character, as well as on their ability to create hydrogen bonds.