Biochem Chapter 6 Carbohydrates PDF

Chapter 6 Carbohydrates I: Mono- and Disaccharides, Glycolysis, Gluconeogenesis, and the Fates of Pyruvate Biochemistry First Edition John Tansey Lecture PowerPoints Tanea Reed/ Dr. Jose Sapien Chapter 6 Outline 6.1 Properties, Nomenclature, and Biological Functions of Monosaccharides 6.2 Propert...

Chapter 6 Carbohydrates I: Mono- and Disaccharides, Glycolysis, Gluconeogenesis, and the Fates of Pyruvate Biochemistry First Edition John Tansey Lecture PowerPoints Tanea Reed/ Dr. Jose Sapien Chapter 6 Outline 6.1 Properties, Nomenclature, and Biological Functions of Monosaccharides 6.2 Properties, Nomenclature, and Biological Functions of Complex Carbohydrates 6.3 Glycolysis and an Introduction to Metabolic Pathways 6.4 Gluconeogenesis 6.5 The Fates of Pyruvate Copyright © 2019 John Wiley & Sons, Inc. 2 Carbohydrates Defined ▪ Carbohydrates are a group of biological molecules with the basic formula Cx(H2O)x. ▪ 1 carbonyl group (C=O) and the others hydroxyls (-OH) ▪ Examples of polyhydroxy aldehydes or polyhydroxy ketones Copyright © 2019 John Wiley & Sons, Inc. 3 From: https://microbenotes.com/carbohydrates-structure-properties-classification-and-functions/ Copyright © 2019 John Wiley & Sons, Inc. 4 Monosaccharides Defined ▪ Monosaccharides are the simplest carbohydrate (contain one sugar). • Can be linked to form more complex carbohydrates • End in suffix “-ose” • Must contain at least three carbons • Can be catabolized into pyruvate Copyright © 2019 John Wiley & Sons, Inc. 5 Monosaccharide Classification (1 of 2) ▪ Based on the following criteria 1. number of carbons (3-9) 2. presence of aldehyde or ketone o aldoses vs. ketoses From: https://www.toppr.com/ask/content/posts/aldehydes-ketones-and-carboxylic-acids/notes-28879/ Copyright © 2019 John Wiley & Sons, Inc. 6 Copyright © 2019 John Wiley & Sons, Inc. 7 Monosaccharide Classification (2 of 2) 3.- Based on stereochemistry of the penultimate carbon • D isomer if the hydroxyl group is on the right • L isomer if the hydroxyl group is on the left • Nearly all carbohydrates found in nature have D stereochemistry • Different stereoisomers give the molecule a different final shape Copyright © 2019 John Wiley & Sons, Inc. 8 First Fifteen D-Aldoses Because glucose is the most common D carbohydrate, glucose is also called dextrose, particularly in clinical situations. Figure 6.2 First fifteen D-Aldoses. The most common of these molecules found in biochemistry are glucose, mannose, galactose, ribose, and glyceraldehyde. Copyright © 2019 John Wiley & Sons, Inc. 9 Seven D-Ketoses Figure 6.3 Seven D-Ketoses. The most common of these molecules found in biochemistry are fructose, xylulose, and dihydroxyacetone. Copyright © 2019 John Wiley & Sons, Inc. 10 Conformation of Furanoses and Pyranoses Figure 6.5 Conformation of furanoses and pyranoses. A. Furanoses adopt an envelope-like structure with one member of the ring out of the plane. B. Pyranoses can adopt a number of conformations, shown are the chair and boat forms. Copyright © 2019 John Wiley & Sons, Inc. 11 Epimer Defined ▪ Epimer: conformation when carbohydrates differ at one stereocenter. ▪ Examples include glucose and galactose (C-4 epimer) Copyright © 2019 John Wiley & Sons, Inc. 12 Anomeric Carbon Defined ▪ Anomeric carbon is the former carbonyl carbon from the hemiacetal/hemiketal. ▪ α – OH on bottom face of ring ▪ β – OH on top face of ring Figure 6.4A Most monosaccharides will form hemiacetal or hemiketal structures. The formation of a new chiral center (from the old carbonyl carbon) results in an uneven mix of α and β anomers. Copyright © 2019 John Wiley & Sons, Inc. 13 Mutarotation Defined ▪ Mutarotation is the process of converting from one anomeric form to the other. ▪ α – OH on bottom face of ring ▪ β – OH on top face of the ring Figure 6.4B Most monosaccharides will form hemiacetal or hemiketal structures. Cyclic structures can open and reclose, rearranging from one anomer to another, a process known as mutarotation. Copyright © 2019 John Wiley & Sons, Inc. 14 Haworth Projections ▪ Monosaccharides in their cyclic form ▪ Pyran and furan rings Copyright © 2019 John Wiley & Sons, Inc. 15 Chemically Modified Monosaccharides ▪ ▪ ▪ ▪ ▪ Amino sugars Acylation Sugar alcohols (no ring = low calories) Sugar acid (oxidized) Deoxy sugars Copyright © 2019 John Wiley & Sons, Inc. 16 Glycosidic Bonds Defined ▪ Glycosidic bonds are the linkages that join monosaccharides to each other, proteins, lipids, or peptides. ▪ Can occur through amines or hydroxyls Copyright © 2019 John Wiley & Sons, Inc. 17 Example of Glycosidic Bonds From: https://ib.bioninja.com.au/standard-level/topic-2-molecular-biology/23-carbohydrates-and-lipids/sugar-subunits.html Copyright © 2019 John Wiley & Sons, Inc. 18 6.1 Concept Check What classification is the following monosaccharide? a. b. c. d. aldopentose aldohexose ketopentose ketohexose Copyright © 2019 John Wiley & Sons, Inc. 19 6.1 Concept Check What classification is the following monosaccharide? a. b. c. d. aldopentose aldohexose ketopentose ketohexose Copyright © 2019 John Wiley & Sons, Inc. 20 6.1 Concept Check Mannose is a ___ epimer of glucose. a. b. c. d. C-1 C-2 C-3 C-4 Copyright © 2019 John Wiley & Sons, Inc. 21 6.1 Concept Check Mannose is a ___ epimer of glucose. a. b. c. d. C-1 C-2 C-3 C-4 Copyright © 2019 John Wiley & Sons, Inc. 22 Section 6.2 Properties, Nomenclature, and Biological Functions of Complex Carbohydrates Copyright © 2019 John Wiley & Sons, Inc. 23 Polysaccharides Defined ▪ Polysaccharides are polymers of monosaccharides • disaccharides – contain two monosaccharides • trisaccharides – contain three monosaccharides o can serve structural roles or as a stored form of energy Copyright © 2019 John Wiley & Sons, Inc. 24 Examples of Polysaccharides Copyright © 2019 John Wiley & Sons, Inc. 25 Linkages Used to Form Polysaccharides ▪ Dependent on the α or β linkage ▪ Includes the number of carbons involved in the linkage Copyright © 2019 John Wiley & Sons, Inc. 26 Example of Glycosidic Bonds From: https://ib.bioninja.com.au/standard-level/topic-2-molecular-biology/23-carbohydrates-and-lipids/sugar-subunits.html Copyright © 2019 John Wiley & Sons, Inc. 27 Common Disaccharides Figure 6.7 Examples of common disaccharides. The structures of A. lactose, B. sucrose, and C. maltose are shown. Copyright © 2019 John Wiley & Sons, Inc. 28 Common Disaccharide: Lactose ▪ Milk sugar ▪ Consists of glucose and galactose through a β-1,4 linkage ▪ Degraded by lactase Copyright © 2019 John Wiley & Sons, Inc. 29 Structure of Lactose Figure 6.7A Examples of common disaccharides. The structure of lactose. Copyright © 2019 John Wiley & Sons, Inc. 30 Common Disaccharide: Sucrose ▪ Table sugar ▪ Consists of glucose and fructose through an α,β-1,2 linkage ▪ Degraded by sucrase Copyright © 2019 John Wiley & Sons, Inc. 31 Structure of Sucrose Figure 6.7B Examples of common disaccharides. The structure sucrose. Copyright © 2019 John Wiley & Sons, Inc. 32 Common Disaccharide: Maltose ▪ Malt sugar ▪ Consists of two glucose molecules an α-1,4 linkage ▪ Degraded by maltase Copyright © 2019 John Wiley & Sons, Inc. 33 Structure of Maltose Figure 6.7C Examples of common disaccharides. The structure maltose. Copyright © 2019 John Wiley & Sons, Inc. 34 Polysaccharide for Energy Storage: Raffinose ▪ Trisaccharide ▪ Consists of galactose, glucose, and fructose ▪ Found in broccoli, cabbage, and Brussel sprouts ▪ Cannot be digested by humans • lack α-galactosidase Copyright © 2019 John Wiley & Sons, Inc. 35 Structure of Raffinose Figure 6.8A Examples of a trisaccharide and oligosaccharide. Shown is the structure of raffinose (found in broccoli, beans, and cabbage). Copyright © 2019 John Wiley & Sons, Inc. 36 Polysaccharide for Energy Storage: Inulin ▪ Oligosaccharide (plants) ▪ Consists of fructose polymers and capped by glucose units ▪ Storage form of energy in plants ▪ Cannot be digested by humans • soluble fiber Copyright © 2019 John Wiley & Sons, Inc. 37 Structure of Inulin Figure 6.8B Examples of a trisaccharide and oligosaccharide. Shown is the structure of inulin (a polysaccharide found in chicory and added to many foods). Copyright © 2019 John Wiley & Sons, Inc. 38 Polysaccharide for Energy Storage: Amylose ▪ Linear polymer of several thousand glucose monomers ▪ α-1,4 glycosidic linkages ▪ 30% of starch ▪ Adopts a helical shape ▪ Insoluble in water Copyright © 2019 John Wiley & Sons, Inc. 39 Polysaccharide for Energy Storage: Amylopectin ▪ Branched polymer of several thousand to several hundred thousand glucose molecules ▪ α-1,4 glycosidic linkages • α-1,6 branch point every 24 – 30 residues Copyright © 2019 John Wiley & Sons, Inc. 40 Polysaccharide for Energy Storage: Glycogen ▪ Storage form of carbohydrate (animal) ▪ Contains several tens of thousands of glucose monomers ▪ Highly branched at every 6 –12 residues • α-1,4 and α-1,6 linkages ▪ Glycogenin core Copyright © 2019 John Wiley & Sons, Inc. 41 Structural Polysaccharides: Cellulose ▪ Structural polysaccharide (plants) ▪ Most abundant biological molecule on Earth ▪ Linear polymers of hundreds to thousands of glucose monomers ▪ β-1,4 glycosidic linkages ▪ Cannot be digested by humans • lack β-galactosidase Copyright © 2019 John Wiley & Sons, Inc. 42 Structure of Cellulose Figure 6.9A Structures of cellulose, chitin, and alginate. Shown are the repeating units of the structural carbohydrate cellulose. Copyright © 2019 John Wiley & Sons, Inc. 43 Structural Polysaccharides: Chitin ▪ Structural carbohydrate (fungi and exoskeletons of arthropods) ▪ β-1,4 glycosidic linkages of N-Acetylglucosamine ▪ Greater strength than other polysaccharides Copyright © 2019 John Wiley & Sons, Inc. 44 Structure of Chitin Figure 6.9B Structures of cellulose, chitin, and alginate. Shown are the repeating units of the structural carbohydrate chitin. Copyright © 2019 John Wiley & Sons, Inc. 45 Structural Polysaccharides: Alginate ▪ ▪ ▪ ▪ Structural polysaccharide (brown algae and kelp) Copolymer of glucaronate and mannuronate Highly ionic Water soluble Figure 6.9C Structures of cellulose, chitin, and alginate. Shown are the repeating units of the structural carbohydrate alginate. Copyright © 2019 John Wiley & Sons, Inc. 46 From: https://ib.bioninja.com.au/standard-level/topic-2-molecular-biology/23-carbohydrates-and-lipids/sugar-subunits.html Copyright © 2019 John Wiley & Sons, Inc. 47 6.2 Concept Check Cellobiose can be used to detect malabsorption syndrome. It can be classified as a ___________. a. b. c. d. monosaccharide disaccharide trisaccharide oligosaccharide Copyright © 2019 John Wiley & Sons, Inc. 48 6.2 Concept Check Cellobiose can be used to detect malabsorption syndrome. It can be classified as a ___________. a. b. c. d. monosaccharide disaccharide trisaccharide oligosaccharide Copyright © 2019 John Wiley & Sons, Inc. 49 6.2 Concept Check Based on the structure of cellobiose, it has a ______ glycosidic linkage. a. α-1, 2 b. α-1, 4 c. β-1, 2 d. β-1, 4 Copyright © 2019 John Wiley & Sons, Inc. 50 6.2 Concept Check Based on the structure of cellobiose, it has a ______ glycosidic linkage. a. α-1, 2 b. α-1, 4 c. β-1, 2 d. β-1, 4 Copyright © 2019 John Wiley & Sons, Inc. 51 Copyright Copyright © 2019 John Wiley & Sons, Inc. All rights reserved. Reproduction or translation of this work beyond that permitted in Section 117 of the 1976 United States Act without the express written permission of the copyright owner is unlawful. Request for further information should be addressed to the Permissions Department, John Wiley & Sons, Inc. The purchaser may make back-up copies for his/her own use only and not for distribution or resale. The Publisher assumes no responsibility for errors, omissions, or damages, caused by the use of these programs or from the use of the information contained herein. Copyright © 2019 John Wiley & Sons, Inc. 52