in this lesson we're going to talk about how to memorize the amino acids and the best way to do that is this to simply draw it you can try to memorize just by looking at the the structures but it doesn't work the same way as if you draw each individual amino acid and so i highly recommend that you look at the structure and practice drawing it and that's going to help you solidify the these amino acids in your mind you may have to draw a few times but if you take the time to do that then it's going to help you to memorize it so let's begin the first thing that i would draw is a carbon atom every amino acid has a carbon with four bonds on one side of this carbon atom you have the carboxylic acid functional group on the other side you have an amino group thus it's called an amino acid it's the combination of an amine plus a carboxylic acid there's always going to be a hydrogen atom and the fourth piece of every amino acid is the r group and so if you memorize this the only thing that you need to change or adjust is the side chain the r group because that's where every amino acid will differ so just keep that in mind now the first one we're going to talk about is glycine glycine abbreviated gly is the most simplest amino acid and it has the r group of a hydrogen atom so that's the first amino acid that you should convince memory now the next amino acid that we are going to draw is alanine abbreviated ala so let's start from the beginning again so we have a carbon a carboxylic acid functional group a hydrogen atom and an amino acid functional group so that's the basic structure of almost all of the amino acids now alanine differs from glycine in that it has a methyl group instead of a hydrogen group as the r group now anytime you see basically a hydrocarbon side chain the amino acid is considered to be a nonpolar amino acid so if the hydrocarbon chain is mostly i mean if the r group is mostly carbon and hydrogen atoms then you know you have a nonpolar amino acid it's also known as an aliphatic side chain amino acid now let's go over the next example and so the next one we're going to talk about is valine abbreviation v-a-l now for valine it too is a nonpolar amino acid attached to this chiral carbon atom it has four different groups there's going to be a ch group which is attached to two methyl groups and so this is another nonpolar amino acid it has a nonpolar side chain and so that's the structure for valine now the next one that we're going to talk about is leucine abbreviation l e u and this one is also a nonpolar amino acid it's going to have a ch2 group attached to a ch group followed by two methyl groups and so that's the structure of leucine it too has a hydrocarbon side chain which makes it nonpolar now the next one we're going to talk about is isoleucine and i like to think of this as an isomer of leucine the abbreviation for it is ile so first attached to the chirocarbon is going to be a ch group which has a methyl group and an ethyl group so that's the structure for isoleucine the next one that we're going to consider is serine you can also write s-e-r now serine is not a non-polar amino acid but it's a polar one and the r group has a ch2 and an oh group so typically when you see a hydroxyl group it usually makes the molecule polar so this is a polar amino acid which means that it can dissolve well in water so that's serine next up we're going to talk about another polar amino acid called threonine thr now this amino acid also has a hydroxy group so the first group is the ch group and attached to that there's a methyl group and an oh group so this is the polar portion of the side chain group and this portion is nonpolar so anytime you have a hydrocarbon it's always going to be nonpolar but overall because you don't have many hydrocarbons but you do have a polar group this entire molecule is considered to be a polar amino acid now let's move on to the sulfur-containing amino acids and so the first one that we're going to talk about is cysteine abbreviation cyst now cysteine contains a ch2 group and an sh group also known as a thio group now many textbooks will say that cysteine is a polar amino acid whereas i've seen a few diagrams that say that it's a non-polar amino acid so i'm going to leave it up to you to figure out that point now cysteine is a special amino acid it can form disulfide bridges upon oxidation so that's a property of cysteine that you need to know now let's move on to our next example which is going to be methionine methionine is another sulfur-containing amino acid abbreviated m-e-t so methionine has a ch2 group and another ch2 group attached to a sulfur atom which is attached to a methyl group and this is definitely considered to be a nonpolar amino acid because of all of the hydrocarbons in this chain so that's the other sulfur containing amino acid that you need to be familiar with methionine now the next one in the list will be one of the acidic amino acids and this one is known as aspartate abbreviated asp and what makes it acidic is that it has another carboxylic acid functional group so aspartate has a ch2 group and then another carboxylic acid functional group so anytime you see this extra carboxylic acid functional group you know you're dealing with an acidic amino acid it's also a charged amino acid it's electrically charged so anytime there's a charge in the r group it's also considered to be a charged amino acid now the second acidic amino acid that you need to be familiar with is glutamate now notice the ending of the word eight when you see that it tells you that the r group contains a carboxylic acid so that's a good indication that you're dealing with an acidic amino acid glutamate is abbreviated glu and the structure for it looks like this the only difference is there's an extra methylene group or ch2 group so glutamate has an extra carbon in its structure compared to aspartate now the next amino acid that i'm going to draw is asparagine or asparagine it's abbreviated a s n now this particular amino acid is considered a polar amino acid and we're going to talk about why but let me draw the structure first so the r group for asparagine has a ch2 group and then it contains an amide functional group now as you can see the amide functional group has hydrogen bonds like a hydroxyl group and so that causes the side chain to be polar and so this is why it's considered to be a polar amino acid so if you see an amino acid with an amide functional group know that it's a polar amino acid and so that's asparagine now before i move on to the next amino acid i want you to compare the structures of asparagine and aspartate notice that they both contain two carbons they contain one ch2 group and another carbon atom now in aspartate it ends with a carboxylic acid in asparagine it has an amide now consider the similarities between the next one which is going to be glutamine glutamine is going to be very similar to glutamate but look at the word amine glutamine it tells you that it has an aim basically an amide functioning group so like glutamate there's going to be an extra ch2 group so i'm going to put another ch2 group and then after that we're going to have the amide functional group and like aspire gene glutamine is also a polar amino acid due to the hydrogen bonds found in the amide functional group now the next structure that we're going to consider is lysine abbreviation l-y-s so like every other amino acid lysine is going to have a carbon a carboxylic acid functional group a hydrogen and an aiming group now i had to redraw because i'm going to need more space to write out the structure for this one now in lysine there's going to be four methylene groups so we have a ch2 attached to another ch2 and then another one and then another one and then at the end we're going to have an amine so when you see an amine in the side chain of the amino acid this is known as a basic amino acid so if you were to put this amino acid in a solution the ph will be above seven if you were to put an acidic amino acid in water the ph will drop below 7 because it's acidic now the next amino acid that i want to talk about that's also basic is arginine the abbreviation a r g now arginine is going to be somewhat similar to lysine and that it's basic but there's going to be some differences instead of having four methylene groups it's going to be three methylene groups and then it's going to be attached to an nh group followed by a carbon double bonded to an nh ii group with a positive charge and another an h2 group and so arginine has a lot of nitrogen atoms it's another basic amino acid and it's also a charged an amino acid and the same is true for the previous one lysine because it had an nh3 plus group at the end it's also considered an electrically charged amino acid so all of the basic and acidic amino acids are charged amino acids now the next amino acid that we are going to consider is known as phenyl alanine abbreviated phe now let's focus on the word alanine because we drew the structure already so if you recall alanine had one carbon atom a carboxylic group a hydrogen and an amino group and then it had a methyl group so alanine only had one carbon atom in its r group so what do you think about phenylalanine well all we need to do is attach a phenyl group to the methyl group so we're going to take off a hydrogen atom because carbon can only form four bonds and we're going to replace the hydrogen with a phenyl group or basically a benzene ring so therefore anytime you see an amino acid with a benzene ring it's also known as an aromatic amino acid because the benzene ring is an aromatic ring now this is also a nonpolar amino acid because as you can see the r group contains only carbon and hydrogen bonds so it's nonpolar now the next one that we're going to consider that's similar in structure to phenylalanine is tyrosine tyrosine has the abbreviation tyr now tyrosine looks exactly like phenylalanine the only difference is that it has an oh group and so it has a polar portion the hydroxyl group is the polar part of the side chain and the benzene ring with the ch2 group that's the nonpolar portion of the side chain now i've seen some textbooks in diagrams they would say that tyrosine is polar because of the oh group whereas others may say that it's nonpolar because of the hydrocarbon chain so i'm not going to say if it's polar or nonpolar i'll leave it up to you to research that so let me take this out however we do have an aromatic ring but know that this portion of the side chain is nonpolar and this portion is polar as long as you understand that then you should be fine now the next amino acid that i would like to talk about is proline abbreviation pro proline is a bit different from the other amino acids the other amino acids has they all have a free nh3 plus group but in the case of proline the nitrogen is part of the side chain so the side chain contains a carbon atom which is basically well this is going to be a ch group so let's write it that way and then another ch2 group and then another ch2 group and i think now this is supposed to be a ch2 and then the nitrogen is attached to this ch2 and there's two hydrogen atoms on this nitrogen atom now it still has a positive charge but that's proline so it's considered a heterocyclic amino acid because this ring doesn't contain only carbon atoms it contains a nitrogen atom so it's considered a heterocyclic amino acid it's also considered a nonpolar amino acid because the majority of the r group contains only hydrocarbons and this is always there for all amino acids the nitrogen with the positive charge and so that's the structure of proline it's not aromatic this is not an aromatic ring next is histidine abbreviation h i s now histidine is similar to the other amino acids in that the chirocarbon has a hydrogen a carboxyl group and also an amino group now histidine is going to have a methylene a methylene group rather in its r group and it's also going to have an aromatic ring i'm going to draw the line structure for this one so it looks something like this we're going to have an nh group here a nitrogen on this side with a hydrogen attached to it and it's a five-membered heterocyclic ring so this is one two three four five there's five atoms in that ring and since they're not only carbon atoms it's another heterocyclic ring so because this ring is aromatic there should be a double bond here by the way this is an aromatic amino acid it's also an electrically charged amino acid and it's also a basic amino acid this nitrogen here is a basic nitrogen atom but not this one the lone pair on this nitrogen atom is part of the aromatic system now the last structure that i would like to talk about is called tryptophan abbreviation trp so like the other amino acids the chirocarbon is going to have a hydrogen a carboxyl group and an nh3 group as common to all other amino acids except proline now like histidine tryptophan is going to have a methylene group but attached to the methylene group we're going to have two aromatic rings instead of just one so i'm going to draw the line structure just like before so one of the rings is a heterocyclic ring and the other one looks like a benzene ring but both rings are aromatic and there's a hydrogen attached to that nitrogen atom and so that is the structure of tryptophan and that's how it looks like and it's an aromatic amino acid it's also heterocyclic and for the most part it's a nonpolar amino acid the majority of the r group is nonpolar the only portion that's polar is the nh group because it has hydrogen bonds anytime o is attached to h or n is attached to h you're going to have some hydrogen bonds present however because the majority of the r group is nonpolar it's mostly hydrocarbons this amino acid is typically classified as a non-polar amino acid even though it has a small polar group so that's it for this video so for those of you who really want to memorize the structures of the amino acids i highly recommend that you take the time to draw it feel free to rewind the video and draw each structure hopefully before i draw it on the board so you can see if you have it right so test yourself feel free to go back and as i write down every name before i draw the structure pause the video and draw yourself see if you can remember what each structure looks like and that's basically it for this video i hope that uh you found it to be useful and if you do feel free to comment or like this video and thanks again for watching