And the way that they synthesize our proteins is by using the genetic code to translate the sequence of nucleotides into the sequence of amino acids. And we synthesize the polypeptides in that fashion. Now our polypeptides, once they're actually synthesized in the ribosome, are not complete before they actually arrive at the target location. And before they are activated, they have to undergo many different types of processes, many different types of modifications. And together all these modifications are known as posttranslational modifications of our polypeptide chains. Now the types of posttranslational modifications that we're going to briefly discuss in this lecture are shown on the board.