 Now, the next point, you must have seen in the book, they write D-glucose or L-glucose like that. Okay? So, what is this D and L configuration we have of glucose, that is what we are trying to understand. So, heading you right down, D, L configuration and L configuration, okay? So for to assign this D and L configuration, we have to take a reference compound, okay? And the reference compound we have here is glyceraldehyde, okay? So, the standard compound here or the reference compound that we take for this purpose is glyceraldehyde. So, a lot of glyceraldehyde is, it is C-H-O, L-dehyde here, O-H one side, this side we have H and here we have C-H-2, O-H, this is glyceraldehyde. Glyceraldehyde is optically active in nature? Yes or no? Yes, sir. It is optically active? Yes, sir. Okay? Why it is optically active? Because we have one- One-caril carbon. Caril carbon. So, there is no symmetry optically active in nature, okay? Now, it is optically active we have. So, we can also write this, you know, formula of glyceraldehyde, O-H this side, H this side, C-H-O and C-H-2, O-H here. Okay? So, this is the fissure projection of glyceraldehyde, right? In fissure projection we always try to write maximum number of carbon atom on the vertical line, okay? That is how it is, it is a fissure projection. Okay? So, this is the reference compound we have taken and what is the reference we have here that in this compound, okay, this carbon is a caril carbon, the second carbon here. If O-H present on right-hand side, if this O-H are there on the right-hand side of this carbon, then this is D-glyceraldehyde and if O-H on the left-hand side, we call it as L-glyceraldehyde. That is the reference we have. On the basis of this only, we will define glucose also, whether it is D-glucose or L-glucose. Okay? So now, let me draw the structure of glucose again here, okay? Equimolar mixture of this two is what? If you take the equimolar mixture of this two, what do you get? Plasmic mixture, optical inactive. And this is optically active, this is optically active. So, this two also we call it as enantiomers pair of each other. Enantiomers, okay? Mirror image of each other, non-superimpossible, hence enantiomers. Equimolar mixture of this two is resting mixture. Okay? So, if O-H on the left side, it is L, O-H on the right side, it is D, that's what we keep in mind. On the car, caral carbon, that's what you need to see. On the caral carbon on the right, it is D. Now, if I draw the structure of glucose here and that is, here we have C-H-O, then O-H on the right, H on the left, sorry, O-H on the right, O-H on the left. First we have right, then left, and then right, O-H, O-H, C-H-2, O-H. And everywhere we have hydrogen present, H here and H here. Now, you see the thing is here, glucose is this. We have to see the position of O-H on the caral carbon. But in case of glycerol dehyde, we have only one caral carbon. Okay? But here we have how many caral carbon? One, two, three, four. And if I have to number this carbon atom, what is the number of this carbon atom? Should we start from this side or this side? Anyone? From the anti-hyde side because it has this thing. The anti-hyde side because it is the primary principal functional group, right? So this is first carbon. This is second carbon. This one is third. This one is fourth. This one is fifth. This one is sixth. All of you understood this? This is the primary functional group. So we have to start numbering from this carbon atom. So one, two, three, four, five, six. Okay? Like I said, we have to see the position of O-H on the caral carbon. In case of glycerol dehyde, it is very fine because we have only one caral carbon. Here we have four caral carbon. Right? So which carbon we have to see here? Right? So we'll see the carbon which is at the maximum distance from the primary functional group, got it? Okay. Understood? So to define whether it is D or L glucose, we have to see the position of O-H on the caral carbon, which is at the maximum distance from the primary functional group, which is nothing but this C5 carbon. Okay? So if you write this O-H on the right-hand side on this carbon, this is D glucose. Is it clear? This is D glucose. So we have to see it is the configuration of C5 carbon number five. If I take this O-H on the left-hand side, if I write which is suppose this one, we have C-H-O here. O-H on the right. O-H on the left. O-H on the right. O-H on the left. O-H on the right. On the left. This side we have H here. And here we have C-H2. O-H. Everywhere we have hydrogen. So you see on the caral carbon, which is at the maximum distance from the primary functional group, O-H is present on the left. This formula is for L glucose, not D. Clear? Got it? D and L? Yes, sir. Sometimes, you know, the representation of glucose, they also ask this question. Exam may they have asked this question once. Okay? Like suppose at second carbon, what is the configuration we have? D or L? At second carbon. This one at second carbon, what is the configuration we have? See at second carbon, the O-H is present on the right. It means it is D. So 2D. Third carbon. O-H on the left. 3L. 4D, 5D. 5D. So this also they ask the representation of glucose. They'll give you this kind of four options. You have to find it out. Which one is the glucose? D or L? Okay? What is the representation we have? 2D. 3L. 4D. 4D, 5L. This is the representation of L glucose. Is it clear? Yes, sir. So you always see the position of O-H from primary function. The carol carol which is at the maximum distance from the primary function. Okay? Now, next we have to discuss here the classification of carbohydrates. Okay? Classification. Three types of carbohydrates we have mainly. Three types of carbohydrates. The first one is mono saccharides. The second one is oligosaccharides. And the third one is polysaccharides. Okay, so this is Stravon, sir. The ketone group for example, R-C-O-R and both are the same. But less carol carol has different configurations and what do we take? I did not get it, Stravon. Sir, I'll send a picture of the thing on WhatsApp. Okay, I'll see. I'll send it after class, sir. I'll see. Where is the, where is my Yashwantpur's children? Where is that Yashwantpur, guys? Here, sir, here. Where he is, sir? He's there for us. Where is Aditya? I'm here, sir. Okay, and what about the girls? Yes, sir, we're here. You're there? Yes, sir. Okay, so mono saccharides are those carbohydrates which cannot be hydrolyzed further. Okay? Hydrolysis is not possible for these kinds of hydrides. So write down, mono saccharides are those carbohydrates which cannot be hydrolyzed further. For example, we have glucose, galactose, etc. All these are examples of mono saccharides. Okay, oligosaccharides are those carbohydrates which on hydrolysis, which on hydrolysis gives 2 to 10 units of, 10 units of mono saccharides. Example sucrose. 10 units of mono saccharides. Example sucrose. Who's this? Sir, Santosh. Santosh. Sucrose, sir. Can you mute the first piece? 3-O plus. Sucrose on hydrolysis gives 1 unit of glucose. This you must remember. Hydrolysis of sucrose gives 1 unit of glucose and 1 unit of fructose. This also they have asked in the exam. Sir, molotov gives you 2 glucose, right? Molotov gives 2 glucose, yes. Formula of sucrose is C12H22O11. Second example we have maltose. Sir, there's something which gives glucose and galactose, right? Yes, there are other students also guys. S3O plus. Maltose on hydrolysis gives 2 unit of glucose. All of you must remember this. What we get on hydrolysis of these oligosaccharides. Lactose. Lactose, molecular formula is again same. C12H22O11 on hydrolysis. It gives 1 unit of glucose and 1 unit of galactose. So how do we know this? See in all these molecules glucose is common. If you have sucrose, sucrose will get fructose. Lactose, galactose and for maltose we have only glucose. Got it? Another thing here is like you must have heard about disaccharides, trisaccharides, right? What are disaccharides? You can define this as we are defining monosecarides, right? Disaccharides are those carbohydrates which on hydrolysis gives 2 monosecarides. Got it? Disaccharides, trisaccharides. Since this oligosaccharides contains 2 to 10 units. So disaccharides is within this oligosaccharides. Trisaccharides within this oligosaccharides. Tetra oligosaccharides. So all these are sucrose, maltose, lactose are the example of what? Yes? Are the example of disaccharides? Yes or no? Yes. Trisaccharides because on hydrolysis they are giving 2 units. That's why it is disaccharides. Similarly, if on hydrolysis they give 3 units it is trisaccharides and so on which is not important. You don't have to keep that in mind. Now 2 to 10 units are oligosaccharides. One unit if you have monosecarides. What is polysaccharides then? More than 10 units. More than 10 units of monosecarides. Polysaccharides are those carbohydrates which on hydrolysis gives more than 10 units of monosecarides. For example, we have cellulose, starch, glycogen. Yes. So all these are polysaccharides. Copy it down. Can we go to the next page? Let me know. Yes sir. All of you are done?