CARBOHYDRATES

all right now in the previous um in the previous discussion we've learned of the biochemistry or actually the chemistry of lipids and their relevant biological functions and we've learned that there's no unifying feature whatsoever in terms of structure um with the lipids the only thing common through this substances is the fact that they are um insoluble in water insoluble in hydrophobic or hydrophobic substances or in general soluble in organic solvents okay now the um the uh topic of today's discussion are the uh carbohydrates and the carbohydrates are are known to you in sense that um carbohydrates of course are known food sources or energy sources and in one way or another then you have um you have encounter these substances today we're going to learn the carbohydrates are not just utiliz source of energy but actually they serve other important functions as well and we've touched on this somehow some time or in previous um as synchronous discussion we've learned that carbohydrates actually are involved in molecular recognition that is or rather in intercellular communication right in the form of the glycolipids as well as in the form of the glycoproteins we're going to see we're going to learn more about this in today's discussion so let us uh begin um all right so carbohydrates have been named as such like carbohydrates they're going to if you're curious like why are they named as such it's because their formulas are are suggest Ive of them being hydrates of carbon like NH H2O c meaning they are just hydrates of carbon but in truth they are not hydrates of carbon so the uh carbohydrates are actually polyhydroxy alcohol or rather polyhydroxy alhida term stuck and so now we're refer to this substance as as carbohydrates all right now today's discussion for example you're going to learn why or at least why some carbohydrates are indigestible like of the major molecular building blocks of cells and I read nucleotides amino acids lipids and carbohydrates carbohydrates are arar most abundant virtually all the foods we eat contain carbohydrates yet there are subtle chemical differences in the way small sugars are connected to form large molecules and this is responsible for subtle differences responsible for very different chemical and biochemical characteristics for very different physiological functions and relevance which means that not all carbohydrates occur in the forms that can be readily broken down as a result cannot digest and use all the carbohydrates we eat for example if we going to notice the carbohydrates would were able to um utilize for example the carbohydrates rice are in the form of starch all right um starch um it's ultimately broken down into maltose which are just two molecules of glucose that are linked together now if you're going to uh and I believe you've already noticed this that GL um um starch is actually comprised of the same substance or actually the same building blocks um as cellulose cell is the substance or is a material that's uh we we call Wood all right wood on your tables for example and then treats these are made up of the same building block as starch starch as I've mentioned is present in D present in Cava for example or in um in almost all food plant plant food stuff so so you're not able to digest cellulose and I don't suggest that you try um eating for example a piece of wood because you won't be able to do that you do not have the enzyme that's necessary to break down cellulose into glucose but there is one not sure if it's an insect but it's definitely considered a best the um I can't remember what it's called in English but um it's the um it's uh it's uh it's um called in Filipino it's called anai all right or termites I think that's termites right so the termites are Thea termites um are are able to digest um cellulose and therefore they tend to um um damage houses all right and structures the cause this termites actually have cellulases and the cellulases are able to digest cellulose into um glucose but unless I'm mistaken it's not actually the termites but there's some some organism that lives within them that uh are able to produce the enzymes necessary for for the um um for Via um for Via um um hydrolysis of cellulose into glucose okay now going back to our discussion the um carbohydrates are varied in structures and varied in forms and you're going to be amazed at the fact that the differences in properties of this carbohydrates are just attributable to their different stereochemistry or the way by which their groups are oriented in space okay they're not like the prot for example whose diversity can be attributed to the fact that they're made up of 20 or so different amino acids right so carbohydrates as we mentioned a while ago are simply the hydrates or they are called um as such because they were originally thought of as hydrates of carbon but in truth they're polyhydroxy alide or polyhydroxy Ketone or a substance that gives these compounds on hydrolysis or in decomposition we you have the term s aride means sugar So when you say monosaccharide that's mean that means simple sugar all right so one a monosaccharide is a carbohydrate that cannot be hydrolized to a simpler carbohydrate an example of that are glucose um Manos galactose we're going to encounter these examples later so the building blocks of all carbohydrates um are the monosaccharides and they have the general formula cnh2 n where n VAR from 3 to 8 now this is this tells you exactly why they thought they are hydrates of carbon if you factor out n here out of the h2n and o n what happens you end up with CN H2O n right so you you they mistakenly thought of it as substances being um hydrates of carbon when they in fact are not so all those are monosaccharides containing an alahh group or call them the alosis and the ketosis have a monos arid that contain a ketone group right okay so the monosaccharides are classified by the number of carbon atoms they have the um um how many carbon atoms for example the simplest carbohydrate is glycer alide and you can see here glycer allhide has one two three it has three carbon atoms all right and it's an example of an Aldos because it has an an alide for a functional group right so it's an example of an Aldos now dihydroxy acetone phosphate is a ketos it has um three carbon atoms so it's it's a triose all right um it's a dihydroxy acetone now trioses are the simplest of all V carbohydrate monosaccharides okay and that's examples are the glycer alide and the dihydroxy acetone okay now glycer allhide contains a steer Center and exists as a pair of inan numers because if you're going to look at this carbon atom of glycer alide and I hope that you still remember that in organic chemistry when a carbon atom is bonded to four different substituents you expect that carbon atom to be a cality center when it gives rise to an anism two substances are mere images but are not superimposable and therefore are isomers of each other they're called stereo isomers but more specifically they are enantiomers all right so we image ster isomers as I've already mentioned are enantiomers so glycer alide we going to look at that carbon of glycer alide it has um four different substituents bonded to it that explains why it is um an Anum it exists a pair of animers it's Kyle okay now we typically um use the Fisher projection in uh representing the structure of carbohydrates again this is something that you have discussed back in organic chemistry and I hope that you still remember um what Fisher projections are so in this case the bonds are written in two-dimensional space or representation showing the configuration of a tetral aeria centers if you will remember the horizontal lines represent bonds that are projecting forward or directed towards you while the vertical lines present bonds that are projecting to the rear are directed away from you the carbon atom at the intersection of the horizontal and vertical lines is not shown but it is understood or it is implied to be carbon atoms okay now here are the uh um The Way by which we write these structures of say for example the glucose it's an aldose because you have an alide functional group and D fructose it's a ketos because you have a ketone functional group again you're going to notice that this carbon carbon number two three four five and six all have hydroxy groups or o that's why we call them polyhydroxy alide and that's why we call this polyhydroxy ketones all right um okay now um in some instances because you can see here that the carbon atom is explicitly written right carbon carbon carbon carbon but in other instances you might not see them being written at all but that is understood to be carbon because the intersections of the horizontal lines and the vertical lines are understood to be stereogenic centers or cality centers in other words understood to be carbon bonded to four different substituents all right now according to the conventions proposed by Fisher there are two kinds of monosaccharide the D monosaccharide is the monosaccharide right that when written as a Fisher projection has the hydroxy group or the o on its penultimate Carbon on the right now what is penultimate ultimate means last all right penultimate means second to the last so when the hydroxy group on its penultimate carbon in other words second to the last carbon is found in the right in that is a d monosaccharide while an L monosaccharide capital L all right capital l and capital D an L monosaccharide is a monosaccharide that when written as a Fisher projection has a o on its penultimate Carbon on the left all right now let's look at this examples this is an example of a d glucose what where are the penultimate carbons of D glucose and D fructose this is carbon number one 2 3 four five six naturally carbon number five is the second to the last carbon or the penultimate carbon all right so so you can see that the hydroxy group is actually found on the right that is why it is a d sugar right it's D sugar the same is true with this it's called def fructose again because it's um it's um hydroxy group is found at theultimate Carbon is found on the right okay okay now the en animers as um we're now going to consider the Aldo thosis when you say Aldo thosis you actually mean those aldoses that have tet means four right Tetra Tetra Pac for example this Four Corners so tetroses have four carbon atoms you call them Aldo tetroses so the enantiomer are stereoisomers are Mir images examples are D and L erros myomer or the isomers that are not miror images and examples are Theos and Theos are diers now let's look at their structures okay to to to to drive home the point that we're trying to make now if you're going to look here the arthos look at that it's called the Aros why because the penultimate carbon the hydroxy group on the second of the last carbon in other words in this carbon is found on the right okay so that's why it's called D Aros its miror image is called lros right and notice that in the case of lros V hydroxy group is actually found on the left as expected all right naturally occurring sugars are the sugars naturally occurring sugars are the um sugars okay now d3o again has a hydroxy group on the right the alos has a hydroxy group on the left now if you're going to consider D fros and lfos what do you say they are non-s superimposable mirror images right and so you call them an anomers what about the um the uh D AR and L Aros this two they are again they are non-s superimposable mirror images that's why we call them animers okay um I want to make sure that we recording and I want to make sure that you're seeing my slides okay it seems like you are okay now okay um now let us ask another question what about the relationship between um the arroo and D frios they are not in animers right because they are not mere images see they are not mere images and so they cannot be animers but they are definitely stereoisomers because they have different Arrangements of groups are of substituents hydroxy groups o and hydrogen around the cality centers around the carbon atoms if you will remember stereo isomers stereo isomers that are not mirror images are called dumers all right stereo isomers that are not mere images are called diesters okay now okay now here's another interesting question what happens if a sugar forms a cyclic molecule first and foremost does that happen actually it does all right the the uh prevalent form of glucose for example in solution is actually a cyclic um a cyclic compound right the cyclization of sugars take place due to interaction between the functional group on distant carbons C1 to C5 to make a cyclic Hemi acetol again hopefully you still remember acetals and Hemi ketals and hemiketals these are terms that you've learned back in in um in uh in uh these are terms you've learned back in organic chemistry all right okay in both cases the carbonal carbon is new chyal center and becomes an anomer carbon atom okay let's examine what that means all right now I give you a moment to look at this um figure and see for yourselves what I mean okay okay now give you a moment to look at that and see for yourselves what I mean when I call them I'm H acetol all right so ouch all right so do you now remember via alcohol the terms that okay um the um substance here it's the alcohol right and this alcohol reacts with an alide to produce what we call a Hemi acetol all right via Hami ACL has the hydroxy group O and you have what is this Bond this carbon oxygen bond is actually an ether right it's actually an ether Bond and a Hemi acetol is actually um a geminal a geminal hydroxy ether right that's that's um um AI acetone now okay the um um now look at what happens that's a reaction between an alcohol and an alide to produce a Hemi acetol now I want you to look at the at the molecule of De glucose and look at it and see that the substance under goes an intr molecular reaction all right okay now if you're going to notice pay attention to carbon number five this is a carbon number five right and carbon number five you see that it has one o or one hydroxy group now that hydroxy group is found here that's the O not the O at Carbon number six but we're referring to the O at Carbon number five this one when you bend orever when you um um this is called a Fisher projection right now when you transform it into a hay projection this is what you're going to get you just let the molecule um what do you call that uh H what's the term you uh let the molecule lie all right sideways that's what I meant you let the molecule lie sideways and you're going to get this structure and we oxygen at Carbon number five is going to attack carbon number one and you're going to form this two cyclic structures and you're going to notice that this double bond o has become an O and that o of carbon number five has become an OC bond this substance is an example of what we call a Hemi acetol all right now when the is found at the bottom we call this an alpha anomer all right an alpha anomer and when the when the oh group is found above you call it a beta a beta animer all right and notice that they have six member drinks and if you remember back in organic chemistry you have chair conformer the chair confirmation right we call this a an alpha D gluco Pano and you call this beta D glucos and we call them as such because of their resemblance to peran this is the structure of paron all right um that's a structure of paron notice that the only difference between their structures that you have one oxygen and there's no double bond here but here there are two double bonds because of their resemble resemblance to pan we call them perosis all right so we have an alpha D gluco Pinos here and the beta gluc paranos here all right okay now this is uh this two are what they call haor projections and again this is Fisher projection if you want to draw them using a Fisher projection the alpha D glucos it's the same thing the only difference is that you have the um um um the here right look at the O here o here carbon number one is found on the right in the case of a beta D gluco parinos in a Fisher projection the O is found on the left now look at configurations around carbon two three and four are they identical for both the Alpha and the beta D gluco Pinos yes right two three and four if you're going to look at them the O as well as the H are found in the same places or in the same relative orientations in the case of carbon number one it's not the case in carbon number number one in Alpha D glucos is found on the right and in the case of carbon number one in beta D gluco Pinos it's found on the left okay again this is the Hayworth projection and this is the Fisher projection okay now monosaccharides have o and couble bond o groups in other words hydroxy and carbonal groups in the same molecule and exist almost entirely as five and six membered cyclic Hami acetol um the truth is the um the truth is the um cyclic structures for this substances are actually more stable compared to the open chain forms and that explains why they primarily are found in the form of cyclic um Hemi acetal again the anomic carbon is a new spor center that results from cyi acetol formation this is the anomeric carbon this carbon number one it's was actually carbon number one before right um this is the anomeric carbon it was previously carbon number one in the open chain form and notice that now it is a new cality center so when the O is found at the bottom again we call that um an alpha animer or when in the fish a projection you find it on the right when it's called an alpha anim if it's um it's found above all right you call that um a beta d gluc opur and uh if it's found on the left in the Fisher projection you call it bet the de gluc data animare all right okay now as you mentioned the animar are carbohydrates different configuration only at their anomeric carbons because again as I've mentioned carbon number two three four and five actually have the same configuration right two three four and five they only differ in their config cation about carbon number one or the anom carbon so we call this Alpha D gluco Pinos and beta d glucos as anomers all right anomers are again example of what we call diasteromers this are an these are stereo isomers that are not en aners or that are not nons superimposable mirror images okay now the five and the six membered Hemi acetol are represented this planer pentagons or hexagons as a case may be of course it's a pentagon if you have five member ring and it's a hexagon if you have a six membr ring and viewed through the edge you're looking at the molecule through the edge most commonly written of the anomeric carbon on the right and the Hemi acetal oxygen to the back right as we're going to show that exactly what that means later the designation beta again means that the o on the anamary carbon is assist to the terminal ch2 while Alpha means that it is trans now look at that this is the alpha the glucos right so it's called a while ago I told you that it's an alpha avoh is found at the bottom but the more technical or the more accurate um um definition is that when the hydroxy group at Carbon number one is found opposite V ch2 at Carbon number five right this is carbon number five and you call that an alpha animer but when the hydroxy group is found on the same side as a ch2 group at Carbon number five and you call that um a beta animer all right that's um that's a more accurate definition okay now I've already remembered this and we already said a while ago that we call it a Pinos because it's it's it's made from it resembles be on right what if you have five membered rings just imagine that you have a bond just remove this ch2 group just remember or imagine that you have a bond here and a bond there you you have what we call a furan a furan and so we call that instead of Pinos you call that furos all right Pinos furos are five membered Hemi accid ring shown by the uh infect um furin or furos and the five member drinks are so close to being pler the haor rejections are adequate to represent fosis they are they're close to being pler but in truth they're not if you will remember back in organic chemistry cyclopentanes actually have what we call um an envelope confirmation it resembles an envelope with a flap open right for a perosis the six member ring is more actually represented as a strain free chair confirmation again this is something that you've already learn back in organic chemistry when you remember cyclohexane chair flipping from one to another all right so this are Behavior representations of the fur no structures again this is Furon all right difference between the fosis and Furon of course is that the Furon has two double Bonds in this case you have no double bonds this one two three and four all right the Hayworth representations of the Pano structures again you have a a on okay now in the case of um of um a five member tring this structure is almost accurate I'm not saying it is accurate I'm just saying it's almost accurate in truth the oxygen Can Be Imagined as actually being skewed up or at least um what do you call that it's um puckered puckered up compared to the four carbon atoms but yes for um to First approximation you can think of it as having a planer structure and you will you will not be entirely right but I cannot fault you for for thinking that way in any case it approximates a pentagon so this is almost an accurate representation but in the case of the Haw projection of alpha D glucose this hayw projection is inaccurate why because glucose does not exist in a in a in a planer confirmation actually exist in a chair confirmation as you can see in this case represented okay and again it will assume the confirmation which the substituents the bulky substituents as much as possible are oriented at the equatorial position so you can see here the O the oh the ch2 the O and the except for the O carbon number one of course they are all found at the equatorial position owing to the fact that this positions are actually more um more spacious they are roomier and therefore bulky substituents can be accommodated better at this positions all right all right now so these are the um Fisher and the Hayworth representations all right so this is um for example for the alpha dluc Pinos this is our Fisher projection for the alpha D glucos and this is for our for our um the Hayworth projection and look at the at the rightmost one it's the abbreviated Hayworth projections and look at how they differ from each other the only differ in that in the abbreviated hay worth projection we actually removed the hydrogens right we uh did not write the hydrogen anymore that makes the representation actually um simpler and more straightforward now look at the beta D glucos in what respect does the alpha D and the beta D glucos differ from each other that's the O in the case of a beta the O is Cy to ch2 at Carbon number five in the case of an alpha the is trans to the ch2 at Carbon number five and this is the beta the Rios and again it's more accurate to refer to that as a beta D RI furos all right beta D riop fur no where again it's data because the O is CS to the um to the uh ch2 at Carbon number four all right um again if you're going to look at that the B the the O at if you're going to look at the Fisher projection the O is found on the left and that is because um it's in the beta configuration remember data is when you have the in the Fisher projection the O at Carbon number one is on on the left in case of an alpha the O is found on the right okay okay now the monosaccharides undergo characteristic reactions and these are reactions that in one way these are reactions that we're actually going to um you're going to encounter next week because I'm going to the to um to the lab um next week in order to shoot this I'm going to to to experiment showing the different reactions of the sugars like monosaccharides and so on so forth and these are Thea these are examples of VAR actions that you're going to encounter now whenever you whenever you encounter sugars you you um at least in in the laboratory setting or even in nutritional settings you you encounter the word reducing end or non-reducing end what does that mean exactly all right it actually refers to whether the substance has an o that is oxidizable into um um um um an Esther or we call that a lactone because it's a cyclic eser where if it's in an open chain form you have an alide that can be oxidized into a carboxilic acid now oxidation of a cyclic Hami acetol gives a lactone when the oxidizing agent is a tol lener agent it's you form a silver mirror and again you have encountered this back in organic chemistry organic chemistry lab this is the silver mirror test where you are able to detect carbohydrates using the silver mirror re I mean using the tollens the tollens reagent all right okay the um Tolen reagent forms silver mirror and so whenever you form that silver mirror then you say the substance is a reducing sugar okay now if anomeric carbons are involved in glycosidic linkage there will be a negative Tolen reg and test we're going to learn more about what is a glycosidic bond later but this is what I want you to um look at this o can be oxidized this can become cble Bond o in other words it can be converted into a lactone that is because that o is still an O if that o is already bonded to say another carbon atom then that can no longer be oxidized and therefore the substance is said to be a nonreducing sugar if the anomatic carbon is not bonded um um if if another anomeric carbon is not bonded and is free there will be a positive Tolen agent test as you can see in this case the O here is not bonded to another uh another I mean the oxygen here is not bonded to a carbon atom in a glycosidic linkage so it's free for reaction and therefore it's said to be a reducing sugar it gives a positive tolin test now you might not be um as familiar to the tolin reagent as you are say for example with Benedict's reagent all right the Benedict's reagent and the reagent all right this reagents actually are colored blue they they have blue Solutions but the copper two plus there is effectively reduced into copper one and it forms copper oxide or cus oxide which is a brick red precipitate and that's why if your solution or your sample tests positive to um to a Benedict solution Benedict test or to a Benedict um to a fing test then that substance is an example of a reducing reducing sugar all right okay um the carbonal group of monosaccharide instead of being oxidized because the process that you've seen a while ago it's called oxidation because youve effectively oxidized the co into cble Bond o in the in the opposite case you can actually excuse me can actually reduce can actually reduce alides and ketones and you will remember that alhida can actually reduce them using catalytic hydrogenation you use H2 and platinum or over platinum padium or nickel you've learned this back in organic chemistry um notice that I've been referring much to organic chemistry because these are organic compounds right and so the chemistries of the substances are not new to you you have learned this back in Dr V's class okay the only difference is that this is you have an hydroxy group and you have a carbonal group all in one in the same molecule so a cble bond o can actually be reduced into an O using a reducing agent reducing agent like as I've already mentioned hydrogen over padium nickel or um platinum as Catalyst or we can use sodium cyanoborohydride all right that's a reducing agent that reduces alides okay now these sorbos all right can be reduced into sorbital look at what happened the cble bond o simply became cohh so what happened is effectively hydrogen has been added to this carbon and hydrogen has been added to that oxygen we call this an Aldos we call this an alol all right Aldos alol so that's Soros become sorbital silol become I mean Sil silos all right has been reduced into silol so an Aldos is reduced into an alol AOL is reducing into the corresponding alcohol okay now the sugars can also form phosphoric Esters all right phosphoric Esters are particularly important in the metabolism of sugars provide energy and we're going to learn more about this when you study glycolysis right for now phosphoric Esters are frequently formed by transfer of a phosphate group from ATP for example this is carbon number six right and you have an O there that oxygen will react with ATP to produce beta D glucose 6 phosphate and that beta D glucose 6 phosphate is what we call a phosphoric esor of um glucose or of a sugar in this case all right now we have mentioned something about the glycosite or like glycosidic Bond or the glycosidic linkage a while ago okay a carbohydrate in which the O of the anomeric carbon is replaced by an O all right remember in the previous examples let's go back to that previous examples for example this is an O all right if that anomeric carbon o is converted from o to OC then that is no longer then then that is what we call a glycosite right as I mentioned here it's a carbohydrate in which the O of anary carbon is replaced by an O so those deres from fosis are called furanosides and those that are D from pirosis are called Panos sides all right and we call the bond glycosidic Bond the bond from the anomeric carbon to the or group this is the basis for the formation of polysaccharides and oligosaccharides saying a while ago a glycoside is when an O at the anim carbon has been replaced by an OC all right and if it's um a glycoside from a Furon it's called furos side and if it's a glycoside from a piranos or Panos it's called Panos sides all right this is the basis for the formation of disaccharides trisaccharide and uh polysaccharides okay okay so here is let me use my pointer so this is Alpha D gluco Pinos and it's again we call that a Hemi acetol because you have a ginal hydroxy ether right you have a hydroxy group and then e for functional group and one in the same carbon now in a substitution reaction um let's use a pointer okay so this is the um Hami acetol and this Hami acetol will react in a substitution reaction with methyl alcohol what's going to happen is that this is going to be replaced by ch3 o or O3 as you can here this is what we call now a glycos bond all right a glycosidic bond this is Alpha D glucos and that's methyl alcohol so we call this now methyl Alpha D glucoside it's a glycoside all right methyl Alpha D glucoside it's a glycoside all right okay now there are two different disaccharides of alpha D glucose all right glycos IC linkages can take various forms remember in the introduction I've mentioned that the carbohydrates um diversity and structure is attributable to the fact that they have this ability to form different to form bonds of the same kind and I I'm I had to emphasize that bonds of the same kind they are all glycosidic linkages they only differ in which carbons are attached to which carbon atoms or which atoms are attached to which atom atoms and the U the orientation in space is it an alpha glycoside or a beta glycoside okay and this will be very interesting now now let us look at the structure here as I've mentioned two different disaccharides of alpha D glucose um are found in nature so um glycosidic linkages can take various forms the anomic carbon of one sugar to any of the O group of in over sugar to form an alpha or beta glycosidic linkage let's go back to the previous example if you're going to notice this is Alpha de gluco Pinos and that's methyl alcohol right this actually can be any alcohol for as long as you have an O group so that means instead of methyl alcohol you can actually have another molecular of glucose reacting with it right this is one molecule of glucose this is another molecule of glucose and how do you number them this is carbon number number one so this is also carbon number one but this is carbon 1 2 3 4 so that's an alpha why is it called Alpha because again the O of this carbon atom is rather the oxygen of this glucose residue is found opposite to the ch2 that's why it's called Alpha the glucose on the left has an alpha configuration at the anomatic carbon it's 14 Alpha 14 why because this is carbon number one of the glucose on the left for the monosaccharide on the left and this is 1 2 3 four carbon number four of the monosaccharide on the right so that's why it's called alpha4 glycosidic linkage it's actually called to be more specific it's an glucosidic linkage because that's a glucose right glucosidic Bond now this is another it's an alpha one6 glycosidic Bond why because instead of being bonded to carbon number an oxygen at Carbon number four you have it's bonded to an oxygenate carbon number six yeah have 1 2 3 4 five six right so it's an alpha6 glycosidic Bond or glycosidic linkage right now Alpha 14 and alpha6 glucosidic linkages are actually found in starch okay all right and we're going to learn more about that later now these are the uh substances that you're going to um find most important in blood types because this substances are actually found on surface of cells in the form of glycolipids or glycoproteins as I've mentioned before it's the the kind and the uh sequence of um poly saccharides that determine blood types all right like uh what what are your um I'm thinking I'm trying to remember the term be used for for that um epitope the epitope so the particular epitopes that are presented on the uh on the um um surface of arthrits or red blood cells these are naacl beta glucosamine and naacl mamine acid okay now we call them Amino sugars because they have amine groups like here you have a carbon number two right you have an NH and you have here at Carbon number two you have another NH all right so this is n acetal beta D glucosamine and this is n acetol muramic acid okay sugars can undergo oxidation reactions as well as formation of Esters all right yidic linkages can be formed between monosaccharides of different kind as we've seen a while ago in the case of the alpha 14 and Alpha one6 glycosidic linkages and the glycosidic linkages are responsible for the bonding of monosaccharide to form oligosaccharides and polysaccharides it's just like what amino acids forming oligopeptides and polypeptides right okay now let's consider the disaccharides because these are the substances which you're most SAR with in the sense that you encounter them almost every day so sucrose for example it's a it's stable sugar all right and this has one unit of D glucose and one unit of Def fructose that are joined by an alpha12 glycosidic Bond hopefully okay now let's look at that this is sucrose all right this is a structure of sucrose and what you notice you have here um you have here um what weall this is carbon number one right and what is this if you remember that is a glucose residue right and what is this this is a fructose residue a fructose residue so notice that the oxygen here is found trans to the ch2 of carbon number five so that means it's Alpha all right so Alpha so it's glucose Alpha one2 fructose um actually if you want to be more systematic this should be gluco look at how we name them here right um methyl Alpha glucoside so let's let's be uh like that let's be uh systematic so here is that what do you call this you call this gluco and you have six member drain right so it's Pino so it's gluc Co Panos but you have a substituent in the form of a fructose bonded to that so it's called gluco panil all right like methy ethil so just call that gluco piranos okay gluco panil Alpha One and what is this carbon that's carbon number two alpha because this is okay this is your carbon number one for fructose that's carbon number one this is your carbon number two so it's called Alpha One 2 fructo what is a fructose here five member drink so it's called fructo furanoside all right okay so the complete name of this substance of sucrose in other words say for example you're trying to prepare your coffee in the morning and you're you're you're um trying to prepare youre coffee for your father or for your mother say or your parents are trying to prepare coffee for you and then tell them that you want um you want um gluco purosil alpha12 fructo furanoside put into your coffee all right yes because that's just sucrose or table sugar okay now let us consider another one let's consider maltos this is maltose right and if you're going to notice maltose actually consists of two glucose residues like this is glucose and you have your another glucose right um H so what kind of bond do you have this is naturally carbon number one all right so that's glucose and it's also Alpha because the oxygen here is trans of a ch2 Alpha so that's glucose alpha 1 the question is what is here is it four 2 three it's already written here it's Alpha 14 so why is it 14 because this is carbon number one for glucose one 2 3 4 G one two 3 4 look at my pointer one two 3 4 so it's called gluco panil alpha4 glucopyranoside all right that's a systematic name and what is that it's maltose now let me ask you a question is maltose a reducing sugar is glucose or is sucrose a reducing sugar okay what did we say a while ago reducing sugars have o have free o at the anomeric carbon so this o is free this is not free but to be a reducing sugar you just need to have one at least one reducing end this is called our reducing end and therefore maltose is an example of a reducing sugar now if you're going to look at sucrose or here do you see any free o at Carbon number one definitely this is not free it is already in a glycosidic bond right the oh here it's no longer o it's now an O carbon so now in a glyc bond now what about fructose fructose does not have free anomeric um o so it's not a reducing sugar so this sucrose does not reduce Tolen reg agent Benedict's reagent or um um fings reagent okay now let's look at another example and this is another one that is of course in one way or another we' encounter this lactose now let's look at lactose lactose is made of of D galactose and one unit of D glucose joined by a beta one for glycosidic linkage okay now look at that H um why do we call this beta because all our previous examples are alpha now we call this beta because the oxygen here this oxygen is found on the same side as the as the ch2 by the way this is galactose the galactose resue so this is actually galao Panos beta 14 glucose Pano side all right and again this is a free anomeric carbon this is a reducing agent so lactose is an example of a reducing sugar all right now cellu bios these are also two um glucose resut are linked together how does it differ from maltose they only differ actually they are almost the same the only difference is that in maltose it's an alpha4 glycosidic bond in cobos it's a beta one for glycosidic linkage okay now what about in The Case of isomaltose the case of isomaltose it's totally different because it's not alpha or beta difference it's bonded to it's one 4 you see here 14 14 this is six all right six um so they they differ in their bonding Arrangements ISO maltos okay but it's still Alpha like the case of maltose all right now you can see here mentioned of a term epimer now what is an epimer an epimer is it's a dierum of another of another molecule where they differ only in the configuration at one carbon atom all right when ever you see Two Sugars written in their Fisher projections and they are the same they have the same configuration at all carbons except except for one carbon for one stereo Center and those two are called epimers for example galactose is a C4 epimer of glucose that means that they have the same configuration at all carbons except for the configuration at Carbon number four okay whereas the O is found on the right for one it's found on the left for the other one or in the other okay okay now disaccharide sucrose is table sugar consist of glucose and fructose linked by a glycosidic bond and lactose found in milk and and maltose I mean lactose is found in milk and maltose obtained from starch or two other common disaccharides and again in the laboratory activity or that we have discussed for last week remember lactose is responsible or in indigestion um suffered by people who are who are lactose intolerant is attributable to their lacking lactase all right or lactase not being expressed in significant enough concentrations okay now what about the polysaccharides what you encountered or what we discussed are the um um oligosaccharides actually disaccharides about polysaccharides when many polysaccharides are linked together you end up with what we call polysaccharides like polypeptides all right um cellulose it's the major structural component of plants especially wood and plant f all right a linear polymer of approximately 2,800 D glucose units per molecule look at that 2,800 D glucose units per molecule joined by beta4 glycidic bonds and they are fully extended they have a confirmation that are fully extended with alternating 180 degree flips of glucose units we're going to see exactly what those structures are the next and the succeeding slides they have extensive intra and intermolecular hydrogen bonding between chains look at that this is the structure of cellulose all right and again the monosaccharide comprising it is just glucose look at that it's beta beta remember the oxygen is on in the same side as B ch2 at Carbon number five so these are all glucose the glucose residues but this is beta4 um um glucosidic or glycosidic Bond the repeating disaccharide in cellulose is called cobos for example this repeating disaccharide unit is called cobos but if we're going to look at it um cellulose is just made up of of of of of glucose in beta data remember data 14 configuration okay now look at that this is the um Hydro or these are the hydrogen bonds and this is for example one chain okay notice that in one chain the hydroxy groups are hydrogen bonded to the the oxygen for example here is hydrogen bonded to the hydrogen at another glucose residue that's in one chain but the hydrogen is hydrogen bonded to an oxygen at another chain that explains the strength and the rigidity of of cellulose or for example of wood all right or of trees this primarily this substance make up Thea bark of trees that explains their strength and their durability the extensive um hydrogen bonding network with this glucose residues and cellulose exhibit all right now what about starch and you're going to i' I've already mentioned it before starch and um cellulose differ only in that one is a beta 14 the other one is an alpha 14 okay um starch is used for energy storage in plants all right it's a polymer of not beta beta D glucose but alpha glucose and there are two types Amo and Amo so Amo is a continuous unbrunch chains of up to 4,000 Alpha de glucose units joined by alpha4 glycosidic Bonds in other words unbranched so it's just a linear chain amop peptine is a highly branched polymer consisting of 24 to 30 units of D glucose that are joined by Alpha one4 glycosidic bonds and branches that are created or that are made up of Alpha One six glycosidic bonds all right amasis and I think you've already encountered this the past because your saliva for example you remember that in physiology or in anatomy maybe you've learned that somewhere in biology salivary amas amas has an alpha amas is an alpha 14 amales in other words it is an enzyme but breaks down the alpha 14 glycosidic Bond and that is why you're able to digest starch because it has alpha4 glycidic linkages and your enzymes are equipped in digesting that you're equipped with an enzyme that's used for digesting that exactly but you cannot eat wood you cannot eat eat cellulose because you do not have the enzyme you do not have a beta amas you have an alpha amas all right okay okay amasis catalyze hydrolysis of alpha one for glycosidic bonds beta amas it's an exoglycosidase and Cleaves on the non-reducing end of the polymer okay again you do not have beta amas Alpha amas is an endoglycosidase and hydrolysis glycosidic linkage I have to clarify that you do not have cellul the enzyme that Cleaves cellulose Alpha amasis is an endoglycosidase and Endo meaning it Cleaves from within all right not at the end but from within and hydes glycosidic linkages anywhere along the chain to produce glucose and maltose the branching enzymes they catalyze the hydrolysis of the alpha one6 branches of aop pectine now here is what we're talking about this is Amo and again it's Alpha because the oxygen is found opposite the ch2 right they are all de glucose and these are Amo this is Amo okay and you're going to notice that the repeating disaccharide subunit here is maltose this is just maltose okay what about here this is amop pectine amop pectine you have you have this you have the alpha 14 but you also have the alpha6 branch here but each branch of course is Alpha 14 that's Alpha 14 this is Alpha 14 Alpha 14 only the branch is the alpha one six okay Amo and aop now this two polymers actually consist or actually comprises starch okay all right now have you ever and we're you're going to see this in the experiment that I'm that I and MBR are going to perform next week formation of a blue blue complex a blue solution when you add iodine iodine into a starch I mean a sample of starch because you form a starch iodine complex now the iodine this is a molecule of iodine I2 can fit all right within the U helical structure of amilos excuse me and the process giving rise to a blue colored complex okay and that uh if you have taken a um analytical chemistry you would have uh learned the uh use of the starch in um in I iodometry all right okay okay now this is kiteen and I'm not I believe you encounter this um kene is the major structural component of exoskeletons the outer skeletons of invertebrates such as insects and Crustaceans for example um crabs all right or shrimps okay also occurs in cell walls of algae fungi and D consists of units of n Acy beta D glucosamine joined by beta 1 for glycosidic bonds now let's look at that this is we' we've discussed this right Amino sugars this is an N ACL beta D glucosamine and look at that you have a beta 14 right beta 14 linkage beta one for linkage and what is this what is a repeating subunit here it's simply n ACL beta D glucos and that's um what makes up kiteen all right now polysaccharides are also found in the cell walls of bacteria you remember gram positive gram negative cell walls right okay now the procaryotic cell walls are constructed on the framework of the repeating unit Nam n acetol muramic acid and n acet um glucose joined by beta one for glycosidic bonds you would have learned this back in I think microbiology you should have microbiology because you're you're taking up medical laboratory science so you should have learned that um the grand positive gram negative cell walls so here it's the cell walls of the procaryotes are constructed primarily from n aetl muramic acid and N acetal glucosamine look at that is it an alpha or a beta one for it's an Al Al it's a beta right because the oxygen here look at my laser pointer that oxygen is found on the same side as the ch2 and therefore it's an example of a beta 14 glycidic linkage and look at that look at the um the structure of a day form all right look at the structure of a day form okay now that repeating disaccharide is typically found um linked to you remember what this are this is simply an oligopeptide right l alanine d glutamine line d alanine That's a Tetra peptide all right um so these are actually sugars that are what we call um call them um I'm because there's a special there's a there's a term that we use for bacteria um but if this substances are present in um in humans or in mammals we would have called this um glycosaminoglycans all right glyos Amino glycos Amino glycans because they are carbohydrates or glyco and they have amines that's why they're called glycos Amino glycans um okay exactly what I was trying to say the glycosaminoglycans these are po polysaccharides based on a repeating disaccharide where one of the monomers is an amino sugar and another has negative charge due to a sulfate or carboxilate group examples are heparine hyaluronic acid and condroitin sulfate and the Keratin sulfate even the dermatan sulfate okay so hyaluronic acid is a component of the vitrio humore of the eye and the lubricating fluid of joints so for example if you're you know people that are aging or older people the elderly suffer from um joint problems like sometimes their joints actually are painful why because of the fact that um their joints are the lubricating fluids in our joints are hyaluronic acid and the elderly do not have enough of the hyaluronic acid anymore that's why as you get older um it tend to uh feel those um to suffer from those um ailments that uh are typically associated with but typically are manifested in the form of painful joints all right condroitin sulfate and keratan sulfate are components of connected tissue or those that connect for example ligaments and bones okay um um all right the um I'm going to um I'm going to uh put in or put up some clinical correlations and in the clinical correlations I'm going to put up the blood types because that's where the carbohydrates get into the picture the blood type epitopes we're going to I'm going to upload something about the um connective tissues the condroitin and the keraton sulfate as well as the honic acid as well all right okay now as a summary the polysaccharides are formed by linking monomeric sugars through glycosidic linkages starch and glycogen are energy storage polymers or sugars now cellulose and kene are structural polymers because they they confer rigidity to an organism right and polysaccharides are important components of cell walls in bacteria as well as in Plants remember in this one these are an a glucosamine and and a mamic acid I'm trying to remember what they are called in Plants because I I honestly forgot if if these are present in melan system as I've mentioned we we would have simply called them glycosaminoglycans um in in in bacteria I forgot what they're called okay now I've been talking about glycoproteins or at least the blood type epitopes and here they come again the glycoproteins contain carbohydrate units that are coent bonded to a polypeptide chain so antibodies are glycoproteins because they have this carbohydrate groups on them oligosaccharide portion of glycoproteins act as antigenic determinants exactly what I was talking about the uh among the first antigenic determinants is covered where the blood group epitopes or the blood group substances in the Ado system individuals are classified according to the four blood types A B a and o at the cellular level the biochemical basis for classification is a group of relatively small membrane bound carbohydrates for example this okay this is the U if you're I don't know if you're type um type O then let's look at type O look at the residues the residues the circle is a galactose the square is n aetl glucosamine and n aetl galactosamine and the triangle is fucose so if you have this Arrangement if if you have this particular sequence particular arrangement of um of carbohydrates on your blood then you are type O if you are type A then you have you have galactose and aetl glucosamine then you have what galactose and to that galactose is bonded in acetal galactosamine and fucose see that now you're going to wonder what what is the difference between because the difference between Type A and type O is very much obvious type O does not have what n ACL galactosamine bonded to galactose right it just has fucose right but what about type B and type A how do they differ from each other and here you're going to Marvel and be amazed but they are just different in what in the fact they just differ because of the fact that one has this one look at that the one where my laser pointer is pointing you have an acetal galactose I mean bonded to a galactose but in type B you have another galactose bonded to the galactose right instead of of of of n acetol galactose remarkable yes and what is this this is a protein or a lipid protein or a lipid protein or a lipid as I've mentioned they are called glycoproteins or glycolipids and they are found presented on cell membranes okay okay the structure is a blood group antigenic determinants again so you have here type A blood group antigen all right and you have here type B blood group antigen okay okay um sugars can be found in specific bonding arrangement in some proteins and presented on the cell membranes and we call them in the case of blood that deter or Ides or red blood cells that determines the kind of blood that you have right glycoproteins frequently play a role in the immune response because antibodies are actually glycoproteins all right okay now that um ends our discussion on carbohydrates