Draw in the R-groups from memory for each of the nonpolar amin...

Question

Draw in the R-groups from memory for each of the nonpolar amino acids.

Accepted Answer

So this practice problem wants us to draw in the r groups from memory for each of the nonpolar amino acids. And whenever you hear nonpolar, you wanna think about our mnemonic, GAV LIMP, where each of these letters here represents the one letter symbol for each of the nonpolar amino acids. And the first is glycine, g. So glycine is so easy that it just glides right on through. So it's literally just the hydrogen and it's the easiest amino acid to remember. Now the next is actually a, and a represents alanine. And alanine, just like a is the first letter of the alphabet and it's easy to remember, alanine is also easy to remember because it's just a methyl group. So it's just a CH3. And also, just like a is the leader of the alphabet, alanine is also the leader of all of the chiral amino acids. And so you can always start the r group of any of the chiral amino acids just by drawing a simple c h. And we know the hydrogens are gonna change, but you can always just start by drawing a c h. Now, the next is valine, which is a v, and, valine's r group literally looks like a v. So what we could do is just draw our alanine, which is the leader, and then just draw in our v. And so that's the R group of valine. Now leucine is our next one, and leucine is l. And so leucine's R group literally is just a loose extension of valine. So you can see how it's kinda they're all like building off of the previous one. So remembering it in this order is helpful for remembering the structures. So leucine is an extension, a loose extension of valine. And so what we need to do is draw in an extra CH 2 and extend the valine just a little bit more. So you can see this part here is the valine. The valine is this part here. But then it's extended by this extra CH 2 here. So leucine is just a loose extension of the valine. Now the next one on our list is I, and I is for isoleucine. An isoleucine is an isomer of leucine, so we know that it's gonna have the same number of atoms and the same types of atoms, but it's gonna be arranged differently and the arrangement is actually gonna come from being a lopsided valine. So what we can do is just draw valine, let's redraw valine. So now we've got valine and then all we got to do make it lopsided by drawing an extra methyl group in there. And now we've got isoleucine. Pretty easy. Right? Now, the next on our list is methionine or m. And just like its one letter symbol is an m, methionine's r group kind of looks like an m. So what we can do is we can draw in, the m, so it goes up, it goes down, and it goes up. And And then at the very end of our m, it needs to be, there needs to be a methylthiol. So for methionine, it has both a methyl group, a meth, but it also has the thio in there. So that means that it's got to have both a methyl, which is a, again, a CH3, and then a thiol would be the sulfur atom. So we'll put our sulfur here, and then we'll fill in our, m with this methyl group. So now we've got our methylthiol, we've got our m shape up, down, up, down, so it's got our sideways m shape, and that is the R group of methionine. And then lastly, what we've got is p, and p is for proline. And just like a p has a backbone and a loop, the r group has, pretty much looks like the loop of a p. So again, if this is the backbone of the amino acid, proline's r group is the loop of the p of a flipped p. So that's what proline's r group looks like. So you can also think p for pentagon because, again, it's going to look like a pentagon when you finish drawing the r group go on in and fill this in. And so it's r group is actually gonna be, consistent of all methylenes, which are just all c h two's. So we'll put in a c h two here, then we'll put in a c h two here, we'll put in a c h two up here, and then finally, it connects back to the nitrogen, it loops back. And again, the number of hydrogens is different than the number of hydrogens on the amino group for all the other amino acids. And that has to do because it's the only one that has a cyclic R group that connects right back to the amino group. And so, this concludes our practice problem and I'll see you guys in the next one.

Struggling with Biochemistry?

Draw in the R-groups from memory for each of the nonpolar amino acids.

Watch next

Nonpolar Amino Acids practice set