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, Ca...

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 12/9/2024 2 2  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 12/9/2024 HBF - 102 3 3  Introduction Definition: Disaccharides are two monosaccharide units united together by glycosidic linkage. Classification: Reducing disaccharides (lactose, maltose) Non-reducing disaccharides (sucrose) 12/9/2024 HBF - 102 4 4  Introduction 1. Lactose (Milk sugar): - It is formed of galactose and glucose united by β1,4 galactosidic linkage. - It is hydrolyzed by lactase enzyme or by acids into D-glucose and D-galactose. 12/9/2024 HBF - 102 5 5  Introduction 2. Maltose (Malt sugar): - It is formed of two molecules of glucose united by α1, 4-glucosidic linkage. - 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. 12/9/2024 HBF - 102 6 6  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. N.B.: In sucrose, both anomeric carbons are involved in the linkage, thus it is non-reducing It’s hydrolyzed by sucrase enzyme into 2 molecules of glucose. 12/9/2024 HBF - 102 7 7  Introduction 12/9/2024 HBF - 102 8 8  Introduction Oligosaccharides Definition: Oligosaccharides are carbohydrates that contain two or more than two monosaccharides (2-10 units of monosaccharides). 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. 12/9/2024 HBF - 102 9 9  Introduction 12/9/2024 HBF - 102 10 10  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, diarrhea & flatulence.  Infants with this problem must take lactose free milk. 12/9/2024 HBF - 102 11 11  Introduction Polysaccharides Definition: Polysaccharides are composed of more than 10 monosaccharide units linked by glycosidic bonds Classification: Polysaccharides are classified into homopolysaccharides (starch, glycogen & cellulose) & heteropolysaccharides (GAGs). 12/9/2024 HBF - 102 12 12  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.  It is present in large amounts in cereals (rice and wheat), tubers (potatoes and sweet potatoes) and legumes (beans).  Starch is hydrolyzed by amylase enzyme in the digestive system. 12/9/2024 HBF - 102 13 13  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. 12/9/2024 HBF - 102 14 14  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. 12/9/2024 HBF - 102 15 15  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. 12/9/2024 HBF - 102 16 16  Introduction Heteropolysaccharides  These are polysaccharides which are formed of more than one type of monosaccharide unit.  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.  Importance: GAGs are present mainly in the extracellular matrix (ECM) or ground substance in association with other extracellular proteins 12/9/2024 HBF - 102 17 17  Interactive Question 1. One of the following by hydrolysis gives galactose units: a) Maltose b) glycogen c) Starch d) Lactose 12/9/2024 HBF - 102 18 18  Interactive Question 2. A polysacchharide which is stored in animals is a) Glycogen b) Starch c) Maltose d) Cellulose 12/9/2024 HBF - 102 19 19  Interactive Question 3. All the following are homopolysaccharides except: a) Starch b) GAGs c) Cellulose d) Glycogen. 12/9/2024 HBF - 102 20 20  Interactive Question Enumerate ? 1. Two reducing disaccharides 2. Two homopolysaccharides 12/9/2024 HBF - 102 21 21  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. 12/9/2024 HBF - 102 22 22  References 12/9/2024 HBF - 102 23 23