CHO Chemistry 2 - HNU PDF

Faculty of Medicine Academic Year: 2024-2025 Year: 1 Semester: 1 Module: Human Body Function (HBF) 102 Carbohydrate chemistry II By: Dr. Sara Sayed Kadry Abdallah Lecturer Medical Biochemistry & molecular biology, Department: faculty of medicine, C...

Faculty of Medicine Academic Year: 2024-2025 Year: 1 Semester: 1 Module: Human Body Function (HBF) 102 Carbohydrate chemistry II By: Dr. Sara Sayed Kadry Abdallah Lecturer Medical Biochemistry & molecular biology, Department: faculty of medicine, Cairo university 11/21/2024 22  Objectives 1. Define and Classify disaccharides. 2. Recognize the significance of different types of disaccharides. 3. Define and recognize the significance of oligosaccharides. 4. Correlate their knowledge to a clinical situation. 5. Identify the different types of Polysaccharides. 6. Recognize the functional significance of the different types of Polysaccharides. 7. List the properties and functions of monosaccharides, disaccharides, and polysaccharides 11/21/2024 HBF - 102 33  Introduction “Disaccharides” Definition: Disaccharides are two monosaccharide units united together by glycosidic linkage. 11/21/2024 HBF - 102 44  Introduction Classification: Reducing disaccharides (lactose, maltose) Non-reducing disaccharides (sucrose) 11/21/2024 HBF - 102 55  Introduction 1. Lactose (Milk sugar): - It is formed of galactose and glucose united by β1,4 galactosidic linkage. 11/21/2024 HBF - 102 66  Introduction - It is hydrolyzed by lactase enzyme or by acids into D-glucose and D- galactose. - In cases of lactase enzyme deficiency, it will lead to a medical problem called “lactose intolerance”. 11/21/2024 HBF - 102 77  Introduction 2. Maltose (Malt sugar): - It is formed of two molecules of glucose united by α1, 4-glucosidic linkage. 11/21/2024 HBF - 102 88  Introduction - Maltose is the main product of digestion of starch by amylase. - It is hydrolyzed by maltase enzyme or by acids into two molecules of D-glucose. 11/21/2024 HBF - 102 99  Introduction 3. Sucrose (Cane sugar) (Table sugar): It is the table sugar and is present in sugar cane, beets and some fruits. It is formed of glucose and fructose united by α 1,2 glucosidic linkage. 11/21/2024 HBF - 102 10 10  Introduction In sucrose, both C1 in glucose and C2 in fructose are involved in the linkage, thus it is non-reducing. It’s hydrolyzed by sucrase enzyme into glucose & fructose. 11/21/2024 HBF - 102 11 11  Introduction “Oligosaccharides” Definition: Oligosaccharides are carbohydrates that contain three or more than three monosaccharides (3-10 units of monosaccharides). 11/21/2024 HBF - 102 12 12  Introduction Significance: Oligosaccharide chains are linked to lipids or to proteins forming glycolipids and glycoproteins present on the cell surface, having many functions including cell recognition and cell adhesion. 11/21/2024 HBF - 102 13 13  Introduction Clinical correlation: Lactose intolerance (lactase deficiency): ✓ Lactose intolerance occurs when your small intestine doesn't produce enough of an enzyme (lactase) to digest milk sugar (lactose). ✓ Symptoms may include abdominal pain, bloating & diarrhea. ✓ Infants with this problem must take lactose free milk. 11/21/2024 HBF - 102 14 14  Introduction “Polysaccharides” Definition: Polysaccharides are composed of more than 10 monosaccharide units linked by glycosidic bonds 11/21/2024 HBF - 102 15 15  Introduction Classification: Polysaccharides are classified into homopolysaccharides (starch, glycogen & cellulose) & heteropolysaccharides (GAGs). 11/21/2024 HBF - 102 16 16  Introduction “Homopolysaccharides” 1- Starch: ✓ Starch is a homopolysaccharide, formed of glucose units united by glucosidic bonds. ✓ It is the chief storage form of carbohydrates in plants. 11/21/2024 HBF - 102 17 17  Introduction ✓ It is present in large amounts in cereals (rice and wheat), tubers (potatoes and sweet potatoes) and legumes (beans). 11/21/2024 HBF - 102 18 18  Introduction ✓ Starch is hydrolyzed by amylase enzyme in the digestive system leading to formation of maltose. ✓ There are two types of amylases: salivary amylase & pancreatic amylase. 11/21/2024 HBF - 102 19 19  Introduction 2- Glycogen: ✓ Glycogen is the storage form of carbohydrates in human body (animal starch). ✓ It is mainly present in skeletal muscles and liver. ✓ Liver glycogen is to maintain blood glucose level. ✓ Muscle glycogen is to provide the contracting muscle with energy. 11/21/2024 HBF - 102 20 20  Introduction 11/21/2024 HBF - 102 21 21  Introduction Glycogen structure: ✓ Glycogen is a highly branched polysaccharide. ✓ Made up of only glucose units. ✓ Within the branches, the bond is α1,4 glucosidic linkage, but at the branching point, the bond is α1,6 glucosidic linkage. 11/21/2024 HBF - 102 22 22  Introduction 3- Cellulose: ✓ Cellulose forms the principal part of the cell wall of plants. ✓ It is formed of a long non- branched chain of β-glucose units connected together by β1,4-glucosidic linkage. 11/21/2024 HBF - 102 23 23  Introduction Clinical correlation: ✓ It is non-hydrolysable by amylase because it contains a β1,4-glucosidic linkage. ✓ The presence of cellulose in diet (vegetables) is important as it increases the bulk of food, which stimulates intestinal contractions and prevents constipation. 11/21/2024 HBF - 102 24 24  Introduction “Heteropolysaccharides” ✓ These are polysaccharides which are formed of more than one type of monosaccharide unit. 11/21/2024 HBF - 102 25 25  Introduction ✓ The most important heteropolysaccharides are glycosaminoglycans (GAGs). ✓ GAGs are unbranched, long chains heteropolysaccharides, composed of repeating disaccharide units, usually made up of an amino sugar and a uronic acid. 11/21/2024 HBF - 102 26 26  Introduction Classification of GAGs: 1. Sulfate-free GAGs: hyaluronic acid 2. Sulfate-containing GAGs: chondroitin sulfate, keratan sulfate, dermatan sulfate, heparin & heparin sulfate 11/21/2024 HBF - 102 27 27  Introduction ✓ Importance: GAGs are present mainly in the extracellular matrix (ECM) or ground substance in association with other extracellular proteins. 11/21/2024 HBF - 102 28 28  Introduction Functions of GAGs: 1. Structural organization of the extracellular matrix. 2. They form a hydrated gel due to presence of negative charges that form hydrogen bonds with water molecules. 3. Lubricant and shock absorber (resilience). 11/21/2024 HBF - 102 29 29  Introduction During exposure to compression → After relief of compressible compression → resilience 11/21/2024 HBF - 102 30 30  Interactive Question 1. One of the following by hydrolysis gives galactose units: a) Maltose b) glycogen c) Starch d) Lactose 11/21/2024 HBF - 102 31 31  Interactive Question 2. A polysacchharide which is stored in animals is a) Glycogen b) Starch c) Maltose d) Cellulose 11/21/2024 HBF - 102 32 32  Interactive Question 3. All the following are homopolysaccharides except: a) Starch b) GAGs c) Cellulose d) Glycogen. 11/21/2024 HBF - 102 33 33  Interactive Question Enumerate ? 1. Two reducing disaccharides 2. Two homopolysaccharides 11/21/2024 HBF - 102 34 34  Summary Carbohydrates are classified into monosaccharides, disaccharides and polysaccharides. Disaccharides are formed of two sugar units. Disaccharides are classified into reducing and non-reducing. Polysaccharides are formed of more than 10 sugar units. The most important homopolysaccharides are starch, glycogen and cellulose. 11/21/2024 HBF - 102 35 35  References 11/21/2024 HBF - 102 36 36