Now when it comes to the three-letter code for amino acids, we're going to say most three-letter abbreviations are simply the first three letters of the amino acid. And when we say most amino acids, we're talking about 16 out of the 20. That leaves us 4 that don't follow this rule. We're going to say 4 of the 3-letter abbreviations are slightly altered to help identify them phonetically. And that means by sound of speech. And they are asparagine, which is ASN, Glutamine which is GLN, Tryptophan which is TRP, and isoleucine which is ILE. Now, a way to help us remember this is that we have the phonetic three-letter code, and our memory tool here is that asparagine is chilling on 3 tropical islands. So here we have an image of 3 islands, and on each one, asparagine has a chance of just chilling. So here, we have asparagine as asparagus, and I'm chilling on 3 tropical islands. So asparagine, ASN, chilling, GLN on 3 because this is 3 letter code, tropical, and we use tryptophan, islands. So just keep that in mind when you have to remember the 4 amino acids that don't simply use the first three letters of their names for the three-letter code. Now if we come down here, we're going to say amino acid, 3-letter symbols. As we can see, we have the first three letters represent the 3-letter code for a majority of these amino acids, except for the 4 that we've highlighted. So again, remember, asparagine is ASN, then we have glutamine, which is GLN, isoleucine is ILE, and then tryptophan is TRP. So just remember, asparagine chilling on 3 tropical islands. That helps you remember those amino acids are a bit different from the other 16. They don't follow the first three letters of their name when it comes to the three-letter code.