hello organic chemistry students in this video we're going to be covering the concept of carbohydrates now what is a carbohydrate the pure standard definition of a carbohydrate is a molecule made of carbon oxygen and hydrogen now they have to be present in a certain ratio as well we have to have so many carbons twice as many hydrogens but the same number of oxygens so anything that falls into a traditional carbohydrate formula will have this basic formula right here now the most common one that we've seen or you've seen in all of your studies is this one right here C6 h126 this one right here goes into the hexoses types of carbohydrates and what we're looking at here is we can have either glucose present fructose galactose Nanos and all these other ones so it's not just giving us a discrete name of a carbohydrate it's helping us break down into an area of carbohydrates and we're going to talk about that here in this video so let's go ahead and get into some more definitions of what a carbohydrate is a carbohydrate must have at least three carbons present in it that is essential three carbons are required now you must have either one aldah or one Ketone now when we're talking about this we're talking about the standard Al alphatic form of a carbohydrate and I know right now you're like wait what does that mean we're going to get to that in a couple of minutes but in that aliphatic form we have to have at least one aldhy or one Ketone all the other carbons then must have an O group on it just one for standard traditional carbohydrates let's go ahead and look at one of the most simple carbohydrates three carbons long alahh at the Top O over here on the right and an O on this carbon down below how can we abev this this is the line angle formula for this compound notice it's not an actual angle why don't we have to have angles and carbohydrates because every carbon except the one that has the aldhy or Ketone on it has to have an O so while there's no angle right here we know there's a carbon here because of the O group as shown now if I go ahead and show this formula this here is C3 H6 3 let me go ahead and switch this and I'm going to go ahead and put the Ketone in when we put the Ketone in and the two o groups it also has the formula of C3 h63 so it doesn't matter if it's an aldhy or a ketone carbohydrate or what we call an Aldos carbohydrate or a ketos carbohydrate keto for Ketone Al Al for Al alide so we're already seeing that we can take the alahh and break them into aldoses and ketosis what we're going to do next is break them down into their sizes when we look at this these first two right here these are called trios carbohydrates y Tri that stands for three so if we had four carbons it would be called a tetos for four carbons if we had five it would be a pentos if we had six it would be a hexos and seven would be a heptose octos nonos and so on and so forth so we can right now we can now take any carbohydrate and break it down into an Aldos or Tri or Aldos or ketos and then break it down into a trios tetos pentos hexos and so forth so that's the basic way that we narrow down the basic naming of carbohydrates we're going to get into the naming of them here in a little bit but what I'd like to right now is also talk about is the presence of these Oh's really important on the carbohydrates and the answer is absolutely they are now when we look at this lower carbon right here this is an ayal Center meaning it is a non-stereo center there are two hydrogens on that carbon so that carbon Center doesn't matter to us the carbon up above though we have this o group a hydrogen a carbon with an aldah a car carbon with an alcohol this carbon here is a chyro center a stereo center now we can assign the RNs configurations of this but that's not the way standard carbohydrates or biochemists or molecular biologists Define this here instead of using our RNs nomenclature we're going to use something called D or L nomenclature and the DNL is going to refer to where this o group is right here and it is on the right side so this carbohydrate right here is the D form of the carbohydrate so D refers to this being on the right side if I go ahead and Shrink this down for a moment and move it up if I went ahead and Drew this one right here oops this one right here this one is actually the L form of this carbohydrate and I'm going to go ahead and just write the name this is L glycerol alahh and up above this is D glycerol alahh now notice this o group is on the right side this one's on the right side but doesn't matter could I have drawn this o group pointing down or off to the side absolutely it's an ayro carbon it doesn't matter where that o group is whatsoever the D or L configurations are going to come from the highest numbered chyro carbon so DNL is assigned on the highest numbered chyal Center in the carbohydrate c h is our abbreviation for it so what I'd like to do now is go ahead and show a little bit larger of a carbohydrate and let let's assign D and L to it so I'm moving this up so I'm going to draw this long carbon chain and let's do this one right here so first things first is this an alos or a ketos this is an alos so we have an alvos carbohydrate how many carbons are in it we have 1 2 3 4 5 and six so so we have an Aldos hexos is it D or L now we see that there's one o group over here on the left side several on the right so since there's more on the right we're going to call this D right no we look at the highest numbered chyro carbon this is chyro so if we think about the numbering the alahh gets carbon number one here's two 3 4 5 and six chyro center chyro Center chyal Center chyal Center non- chyal or ayal this carbon right here carbon 5 with the O group is our highest numbered chyro Center is that o group on the left hand side or right hand side of this carbon framework it's on the right hand side so this is a d Aldos hexos let me go ahead and put that right up here what's the specific name for it though this is dluc glucose the D glucose ultimately tells us that this glucose has this characteristic to us right here and actually I should not put the D part in there it's right here the glucose tells us that it's an Aldos and a hexos but the name glucose also tells us that carbons 2 four and five are on the same side in terms of their o group carbon 3's o group is on the opposite side it is going to to be the pattern of the O groups left or right that makes the name for these molecules and we're going to talk about this on the next slide that I'm going to show you but really quickly I would like to show you this carbohydrate so here I'm drawing a total of six carbons now when we look at this this is also a Aldos it is is also a hexos but now is it a d or L it's l because our highest numbered chyro carbons on the left side in terms of its o group now if you look at the patterns here carbons 2 4 and five the O's are on the same side carbon 3 is on the opposite isn't that the same pattern here I'm not saying which one's left or right I'm just saying that the O group on carbon 3 is on the opposite side of the other o groups on carbons 2 4 and 5 and it's true so what is this molecule's name this is L glucose how simple of A change is that so minor right it seems like inconsequential this is an energy form for us we eat this we can get 36 or 38 ATP per glucose molecule wonderful if you eat L glucose how much energy do you get out none our body does not have the enzymes to recognize L glucose whatsoever all this is is fiber we excrete it out that's it so the difference of D versus L is very important in terms of biological chemistry super important so now let's go ahead and start to look at this large class of carbohydrates all right now I know this slide can see seem a little overwhelming right here we're going to go ahead and talk about this leftand side right here forget about the right side for right now we don't care about it whatsoever what I want to talk about is the Aldo hexoses and keto hexoses they're one of the most important biological sugars in our body because like I said glucose gives us ATP or I should say glucose can be transformed into energy carriers that can give us ATP what I'd like to show you here is that all of these molecules up above are Aldo hexoses how do they differ in terms of their name it's the way that the O groups on the chyal carbons let me stress that one more time it's how these o groups on the chyal carbons the pattern that they have that's the important one we do not care about that last o group on that carbon 6 it's an a chyro carbon I don't care if that o group is off to the right the left or pointing straight down it does not matter whatsoever so now if all the O groups are on the same side that's called alos and here it's dallos because this o group is on the right hand side so when the O group is on the right hand side and all the O's are pointing on that same side it's alos what would L alos look like you got it l alos would have all of these o groups on the left hand side not the right hand side now if we just switch the C2 carbon from the left I'm sorry from the right to the left we have altrose a totally different carbohydrate now think about what I showed you on that opposite page D versus L glucose energy versus fiber the positioning of these o groups is imperative for their biological function now it comes into the most important one glucose the C3 is on the opposite side of the other O's for glucose it's D when the highest chyro carbon is on on the opposite side or on the right hand side now if you look at glucose versus Manos how do they differ it's just the C2 carbon notice the O here is on the right o here is on the left energy nope no energy here our body has to spend energy to convert Manos into glucose to get ATP out of it so the positioning of these o groups are essential now another very important one that I want to show is this one right here this one is D galactose the C4 and C3 are on the same side C2 and C4 on the same side how does it differ from glucose the C4 glucose up here gives us energy galactose down below we use as a way to excrete toxins from our body our liver will conjugate galactose onto molecules make it water soluble and we can excrete it through our kidneys totally different biological properties now if you're looking at this thinking black and blue right here what does that matter I use this page right here when I'm teaching inperson classes and the ones in blue are the ones that they have to memorize this is a Global Campus class you don't have to memorize these I highly encourage you to learn these because for your major this will be important down the road but you do not have to worry about memorizing these for this class as you have your O notes and textbook available to you on exams and quizzes now down below we're seeing the ketos hexoses the same exact molecular formula as the aldoses what's different the C2 position is a ketone the C1 is an alcohol up above C1 is an alahh C2 is a um alcohol so those are the key differences let me go ahead and ask a quick true or false question in this um we'll look at D fructose so let me go ahead and Circle D fructose true or false there are four chyal centers and the answer is false it is not four when we look at this first carbon right here there's two hydrogens so that's not kyal this o group has four different groups on it so chyro chyro this one four different groups chyro ayal so these three are chyal but up above in glucose these four were chyal why oh the C2 is in play with this o where with the ketosis it's a ketone so the number of stereo centers does change so now for this class what kind of naming could I ask you we're really going to focus in on the hexoses I'm not going to ask you about the pentoses and the tetroses and the trioses the hexoses are the most important ones so I could ask questions such as which of the following structures represents D Manos and you would have to match D Man with one of the options now let's start taking into consideration some of the chemistry here we have these aliphatic sugars all of these aliphatic sugars have secondary alcohols in them and primary alcohols we live in an oxidizing environment remember back when we were talking about the oxidation of alcohols primary alcohols and secondary alcohols can be oxidized to alahh and ketones respectively if you look at glucose 36 or 38 ACP if left in this aliphatic form over time we will oxidize the C6 to a um an alahh those are two aldhy that's not a standard carbohydrate anymore energy is gone we don't get any ATP from that at all we can oxidize the secondary alcohols to ketones oh no energy whatsoever so protecting this from oxidation is very important so in their aliphatic state they are susceptible to oxidation but in their cyclic forms this right here they're more protected from oxidation so how does a glucose become this six-membered ring right here what we are going to talk about right now is that the highest numbered chyal alcohol carbon with the alcohol on it that oxygen will attack the carbon of the carbonal if that's an alahh or a ketone it doesn't matter the highest numbered chyro carbon's o group will attack the carbon yum this is going to be mediated by an enzyme in our body in nature this forms very preferentially because of the ring size that we're forming we're not going to go into those details whatsoever we just want to talk about why this is happening and what the benefit is so when this alcohol attacks this carbon yum we can attack from the top or back face right because double bonds have no facial selectivity so once it attacks we are going to break open that double bond and give electrons to that oxygen we'll transfer the proton from this alcohol onto this oxygen and that is what we're left with right here this hydrogen came from that hydrogen right there post proton transfer so when we're looking at this this alcohol on C5 attacks C1 the alcohol on C5 attacked C1 now what how do these groups position to up and down we'll get to that in a moment why did this just occur we have an alcohol we have an aldah this is a Hemi acety that is why we talked about that chemistry all while ago so important Hemi acle forms of glucose are more stable they help resist oxidation of the sugars and therefore we can get energy out of them now we have to talk about the arrangements of this and what I'm going to ask you to do right now is for little bit of memorization and then a pattern that's going to form from it anytime you have a DEC carbohydrate and we're only going to look at the hexoses here especially in the six membered ranks for a d hexos carbon 6 is always pointing up always if it was L it would be pointing down so now the C2 position is always pointing down C3 is opposite of it so therefore pointing up and C4 is on the same side of C2 so therefore pointing down so if we remember that the C2 on the right hand side is always pointing down we can come up with a pattern of our carbohydrates so if we look at glucose glucose's o is on the I'm sorry we're doing that right here so the O here is on the right hand side so it's going down now when we attack that carbon one if we attack from the top or bottom we get 50/50 and that's what that little squiggly line is representing excuse me but now if we're just looking at this structure right here this is still D glucose but how do we specify that it's in a ring form not aliphatic we have to get more detailed instead of using the squiggly line we're going to talk about the O group going down or the O group going up if the O group on carbon one or whatever that carbon yal was the alahh or the Ketone is down relative to carbon 6 that's the alpha configuration or far away from the C6 if the C1 or whatever the carbon y was O group is pointing up towards the C6 that's beta so we have an alpha and beta D glucose so if I specifically said that we have Alpha D glucose we're in the ring form of this carbohydrate if I just said D glucose we're in the straight chain of it now let's go ahead and come down here and look at D glucose again we can form the alpha we can form the beta and now I'm saying the alpha is minor the uh beta is Major why let's take these Hawthorn protections and put them into chair structures so when we adopt the chair structure we know that this C2 has to be pointing down like we're pointing here C1 is up so that's in an equatorial C3 is up equatorial C4 is is down oh equatorial and C6 is up in an equatorial oh my gosh they're all equatorial and that's why they're major in the alpha D glucose while everything is equatorial but C1 it's that one C1 being an axial position that makes it less stable than the beta Now Beta is more predominant in the cyclic form than Alpha we predominantly use Alpha in our body but here's the important thing don't we remember that Hemi atiles are in dynamic equilibrium with their alide and um alcohol counterparts they are so while we have 99% here and 1% here once this 1% is taken off and metabolized into ATP some of this beta will ring open to the alpha or to the um aliphatic form that can close to some of the alpha and some more of the beta we can then take this use this for energy oh some more ring opens goes to the alpha goes to the beta take that use it for energy this is that dynamic equilibrium this is what allows our bodies to help regulate our energy consumption if everything was just in Alpha configurations immediately we would be burning energy constantly we wouldn't have energy stores so this is a point of regulation in our bodies which is wonderful so now let's go ahead and look at a totally different one let's look at deos D OS has C2 and C4 on one side C3 and C5 on the the other side in the D configuration when we cyze it the C2 is on the left side which means it's pointing up now not down remember when C2 is on the right it's down when it's on the left it's up so C3 has to be opposite so that's down C4 has to be on the same side so that's up C this uh the C6 is always up because we're in the D forms right here why is this one minor why is this one major once again it comes down to the number of groups in Equatorial positions there's more equatorial positions in the beta form than the alpha form how can we say that always if you're looking at one carbohydrate forming beta and Alpha all the alcohol groups are in the same positions except one this carbon right here the C1 position that we call the animic carbon the anomeric carbon is the carbon that becomes the you got it Hemi acety so in organic chemistry I kept saying oh look for the carbon that's both the O and The Ether group and that's what an organic chemist would say I'm now putting on my biochemical hat the carbon that's both the O and the ether is the anomeric carbon or if it's the carbon that's part of the oxygen and the ether as well it's also the anomeric carbon which could be the hemiketal so it's the same term for the same functional groups now this takes time and practice to take any straight chain carbohydrate and to put it into their cyclic forms please don't think you're going to get this immediately you need to practice this take one of these carbohydrates like the alosis and try to put it into its ring form and its chair form and that's how we can figure out which one is more stable than the other glucose is the most stable out of all these because all the O groups in carbon 6 are all equit orial in the beta form every other carbohydrate of the alosis Aldos hosis do not have them all equatorial that's something unique to glucose that's why it is so stable now the one last thing excuse me this process of an aliphatic going into the Beta and d and being able to go back and forth is a process called mutter rotation this is an important term to know anyone in Biochemistry Kinesiology molecular um biology is going to use this term frequently mutter rotation is just talking about the straight form of the aldhy and alcohol compound becoming its cyclic form and ring opening again we already know this from uh Class 2 carbonal chemistry because we know hemiketals and Hemi acetes are in dynamic equilibrium with their aldhy alcohol counterparts mutter rotation is just another term for that same fact so now let's go ahead and take this concept of carbohydrates and apply it to something bigger right now we're showing individual carbohydrates one carbohydrate and this is what we call a monosaccharide hopefully I will be able to spell it correctly so a molecule that just has one sugar or made of one sugar is a monosaccharide let's see what happens when they join together now this is when molecules get big and bad when we take two glucoses we have an alpha glucose here and either an alpha or beta we don't care notice the squiggly line when the C4 alcohol of one glucose joins with the anomeric carbon of another glucose this Alpha D we form maltose now remember glucose is defined as a molecule that has six carbons where carbons 2 four and five hydroxy are on the right side see 3 is on the left that's what glucose represents the D tells us what side the highest ayro carbon's o group is on and the alpha is telling us about the anomeric carbon right here when these two join together two glucoses join together via this type of bond here where this carbon is going Alpha this one doesn't matter because it's not the anomeric carbon that's what's defined as maltose maltose is defined as two glucose oses join together in this Alpha linkage right here now we have an acetel in this case now these two sugars are joined together by an alpha 14 Bond what does that mean here's carbon 1 here's carbon 4 that carbon 1 is in the alpha configuration Alpha 14 so maltos implies or I should say when you see the word maltose It Is Telling You by definition two glucoses join together by an alpha 14 linkage now why is this one alpha maltose and this one beta maltose if I just said the two glucoses have to be joined together by an alpha 14 linkage that's defined in the name maltose this Alpha here is defining this o group pointing down on the Hemi acetel which has dynamic equilibrium with his alahh and alcohol this can ring open this one cannot remember your acety Chemistry they do not ring open spontaneously this is now locked in configuration in this beta maltose this o group is pointing up same side as the C6 so we have an alpha and beta maltose now what if we took two glucoses and joined them together via a beta linkage we would form cell cellulos cellulos is just like maltose they're both made of two glucose molecules what is the difference maltos they're connected by an alpha alpha one excuse me so maltose the two glucoses are connected by an alpha 14 linkage the acety carbon of this back carbohydrate is Alpha in cellulos it's a beta linkage notice beta right here this geometry doesn't change because if I put this up that's no longer glucose that would be a galactose molecule totally different so we're looking at this carbon right here's position and this one right here let me put them as circles or dots so the only difference between maltose and cellulos is how the two sugars are attached together reading your textbook practicing this with our online assignment programs will help you learn this more so now that's if two glucoses are attached together we can metabolize maltose we cannot metabolize cellulos this we can use for energy this one will be only for fiber now if we attach a galactose to a glucose notice galactose to glucose not glucose to galactose the order matters the galactose must be the acety the glucose must be the Hemi acety now if it's connected in a beta 14 linkage we have formed the molecule lactose we've heard of that that's in milk we can metabolize lactose but wait we can't metabolize cellul bilos which is a beta 14 linkage but we can metabolize a beta 14 linkage of lactose that doesn't make sense it does these are three-dimensional molecules the galactose has a different three-dimensional shape than glucose our body can recognize it and metabolize it with the enzymes that we have which we'll be talking about here shortly so mtos and cellular bilos two glucoses one an alpha one a beta linkage lactose a galactose bound to a glucose via a BET 14 Bond sucrose is a glucose connected to a um a fructose down below they are both an acetal and ketal linkage very stable that's why we just have the name super ose there is no hemi acety or hemiketal that's important so here acetal ketal here acetal Hemi acetal acetal Hemi acetal same up here Hemi acetals exist in dynamic equilibrium with its Al alahh and alcohol counterparts so if this carbon ring opened or and this one here or this one here an aldhy would be present that we could reduce use with a reducing reagent that is why these are called reducing sugars and I'll go ahead and Encompass it to the whole page here all these are reducing sugars this one is not the reason why sucrose is not a reducing sugar is is that we do not have a Hemi acetal or a hemiketal they're joined together by their respective anomeric carbons here's the anomeric carbon from glucose the anomeric carbon from fructose wonderful now all these molecules that we just talked about are called disaccharides what about ones that are bigger than two joined together we're going to talk about them now they're called the polysaccharides the first polysaccharide we're going to talk about is if we have multiple cellular bioses attached together so glucose after glucose after glucose attached one after another after another all in a beta 14 linkage so cellulose is glucose is attached together all in a beta 14 linkage this is basically paper starch trees that's what all this stuff is made out of we don't get energy from the two glucoses or glucoses attached to one another via a beta Bond what if they were connected via an alpha linkage that's when we start getting amalo amalo is this Alpha linkage here of glucoses one after another after another so the difference between cellulose and amose is once again the linkage type and it's only talking about multiple glucoses let's talk about the most important polysaccharide glycogen glycogen has an amalo backbone Alpha 14 linkages all across this bad boy right here now we can also have alpha6 linkages right here this here is C1 that's C6 from another one and that is an alpha one6 linkage the alpha6 linkage on the amalo allows us to make a branch chain so as the amalo chain is growing it starts to form the cyclical structure and then we start forming more sugars off the side because of that alpha6 linkage and we can keep attaching more on that C4 this is what allows us to form a huge storage of glucose in our cells glycogen is our immediate glucose storage form in our body so when someone comes up behind you and scares you and you jump out of your seat if you don't have to fight anyone if you're just scared you shake for a while why the fight or flight response was initiated glycon is going to rush through your bloodstream hit uh cells and your body is going to be told I should say your cells are going to be told to break down glycogen to glucose millions of glucose molecules blood into your cell which all go into glycolysis kreb cycle the electron transport chain creating millions of ATP but you don't need to fight or run so what happens to all that energy we shake we're dissipating the energy there so when you're scared so bad like a scary movie or someone coming up behind you and if you don't have to run or anything we're shaking not necessarily because we're still scared it's because we're burning off the extra energy that was just released in case we needed to flee so with that right there this is our introduction I shouldn't say introduction but our video over carbohydrates there is so much more chemistry that we could talk about with carbohydrates this could be an entire class just on its own but these are the important Concepts that you need for your majors and for this class if you have any questions please feel free to email me come to a discussion section or office hour and please make sure to watch the video again and take notes on it I hope each of you are doing well well and I look forward to seeing you soon