Lecture 1: Carbohydrates Metabolism PDF

The Strategy for Teaching and learning is extracted from the Egypt Vision 2030 which is aligned with the sustainable development goals of the united nations UN SDGs (UN SDGs) Universal healthcare system capable of improving health conditio...

The Strategy for Teaching and learning is extracted from the Egypt Vision 2030 which is aligned with the sustainable development goals of the united nations UN SDGs (UN SDGs) Universal healthcare system capable of improving health conditions A high-quality education and training system  Module specification (the learning outcomes) ⬣ 1-1-1-3-a- demonstrate understanding of basic metabolic pathways including carbohydrates, proteins and lipids in both healthy and diseased states. ⬣ 1-1-1-3-b- illustrate the integration of the metabolic pathways inside the body during feeding/fasting states. ⬣ 1-1-6-1-a- recognize the different pathways utilized by the body for energy production in healthy state and how this can be changed in diseased states. ⬣ 2-2-3-1a- describe biochemical assessment methods, principles and instruments used in the lab for determination of various biochemical parameters to diagnose various disorders ⬣ 2-2-3-1b- perform and interpret various biochemical tests in the lab as a member of health professional team. ⬣ 2-5-2-2a- apply the principle of basic biochemical knowledge and metabolism in understanding the etiology and management of various diseases. ⬣ 3-1-1-1a- recognize the changes in metabolism, fastfeed cycle and genetics that are associated with various diseases.  3 Aim of the module ⬣ The aim of this module is to provide students with basic information about various metabolic pathways that occur in several body organs for carbohydrates, lipids, proteins and purines. Moreover, integration of metabolism for various biomolecules during feeding/fasting cycles across various organs of the body will be explained. Laboratory tests will be carried out to measure and interpret the changes in the biomolecular signature for possible diagnosis of various diseases.  Assessment Type Weight % Exam Semester/ Exam/ No. of week Written Coursework Length Coursework Quiz 7 S2 / W3-W4 25 -30 min Assessment Online 3 S2 / W2-10 10 min of the Assignment Practical Practical 30 S2 / W11-W12 2 hours pharm D exam Oral 10 S1 /W15 Variable Unseen 50 S1 /W15 2 hours For each part: The learning material (power point slides ± hand out) is available online.  Assessment Type Weight % Exam Semester/ Exam/ No. of week Written Coursework Length Assessment Coursework Quiz 10 S2 / W3-W4 25 min of the Assignment 5 S2 / W2-W10 Variable Practical Practical 25 S2 / W11 and W12 2 hours pharm-D exam clinical Oral Unseen 10 50 S2 /W15 S2 / W15 Variable 2 hours For each part: The learning material (power point slides ± hand out) is available online.  Biochemistry II Lecture 1 Carbohydrates metabolism-1 By: Dr. Hameis Sleem  Table of contents I II III Digestion of dietary carbohydrates Absorption of carbohydrates Entry of glucose to cells IV Overview of Metabolism Carbohydrates (Read only) ⬣ Organic compounds: Polyhrdoxy aldhydes or ketones  Carbohydrates isomerism (Read only) Compounds that have the same chemical formula but have different structures are called Isomers. Enantiomers Epimers Anomers Carbohydrates (Read only) Glycosidic bond (Read only)  Digestion of dietary I carbohydrates  Digestion of dietary carbohydrates The principal sites of dietary carbohydrate digestion are the mouth and intestinal lumen. The final products of carbohydrate digestion are the monosaccharides: ❑ Glucose ❑ Galactose ❑ fructose Monosaccharides are absorbed by cells of the small intestine.  Digestion of dietary carbohydrates Mouth The major dietary polysaccharides are of plant (starch, composed of amylose and amylopectin) and animal (glycogen) origin. During mastication, salivary α-amylase acts briefly on dietary starch and glycogen, hydrolyzing random α(1→4) bonds, the digest resulting from its action contains a mixture of short, branched and unbranched oligosaccharides known as dextrins. Humans do not produce β(1→4)-endoglucosidases. Therefore, we are unable to digest cellulose, a carbohydrate of plant origin containing β(1→4) glycosidic bonds between glucose residues.  Digestion of dietary carbohydrates Mouth Branched amylopectin and glycogen also contain α(1→6) bonds and dissachrides which cannot be hydrolyzed by α-amylase NB: Carbohydrate digestion stops temporarily in the stomach, because the high acidity inactivates salivary α-amylase.  Digestion of dietary carbohydrates Intestine When the acidic stomach contents reach the small intestine,they are neutralized by bicarbonate secreted by the pancreas. Further digestion of carbohydrates occurs in the small intestine by pancreatic enzymes. There are two phases of intestinal digestion. 1. Digestion due to pancreatic α-amylase. 2. Digestion due to intestinal enzymes : sucrase, maltase, lactase, isomaltase.  Digestion of dietary carbohydrates Intestine 1) Digestion due to pancreatic α-amylase. The function of pancreatic α-amylase is to degrade dextrins further into a mixture of maltose, isomaltose and α-limit dextrin. The α-limit dextrins are smaller oligosaccharides containing 3 to 5 glucose units. Isomaltose is a disaccharide consisting of two glucose molecules linked by an α-1,6-glycosidic bond. In contrast, maltose consists of two glucose molecules linked by an α-1,4-glycosidic bond. Digestion of dietary carbohydrates Intestine 1) Digestion due to pancreatic α-amylase.  Digestion of dietary carbohydrates Intestine 2) Digestion due to intestinal enzymes Enzymes responsible for the final phase of carbohydrate digestion are located in the brush-border membrane of the small intestine. Digestion of dietary carbohydrates  Digestive enzyme deficiency Genetic deficiencies of the individual disaccharidases result in disaccharide intolerance. Lactose intolerance: due to deficiency of lactase, leading to accumulation of lactose in large intestine leading to: ❑ Diarrhea ❑ Abdominal cramps The bacteria will act on this lactose leading to CO2 production causing bloating, abdominal cramps Individuals should decrease milk ingestion.  Absorption of II carbohydrates  Absorption of carbohydrates The duodenum and upper jejunum absorb the bulk of the monosaccharide products of digestion. Galactose and glucose are transported into the mucosal cells by an active, energy- dependent process that requires a concurrent uptake of sodium ions by the sodium- dependent glucose cotransporter 1 (SGLT-1). Fructose utilizes an energy- and sodium-independent monosaccharide transporter (GLUT-5) for its absorption. All three monosaccharides are transported from the intestinal mucosal cell into the portal circulation by yet another transporter, GLUT-2. Na is pumped outside the cells by ATPase Na/K pump Absorption of carbohydrates Absorption of carbohydrates III Entry of glucose to cells  Entry of glucose to cells Glucose cannot diffuse directly into cells but enters by one of two transport mechanisms: A) Facilitated diffusion B) ATP-dependent Na+- transport system monosaccharide (Glucose transporters: cotransport system. GLUTs).  Entry of glucose to cells A) Facilitated diffusion transport system (GLUTs) Family of 14 glucose transporters found in cell membranes (GLUT-1 to GLUT-14) Extracellular glucose binds to the transporter, which then alters its conformation, transporting glucose across the cell membrane. In facilitated diffusion, a) Glucose movement is down a concentration gradient (from a high glucose concentration to a lower one) b) Does not require energy.  Entry of glucose to cells A) Facilitated diffusion transport system (GLUTs) Glucose transporters Location GLUT-1 erythrocytes and the blood–brain barrier GLUT-2 liver, kidney, and β cells of the pancreas GLUT-3 neurons and brain. GLUT-4 muscle and adipose tissue, (insulin sensitive) GLUT-5 small intestine and the testes (for fructose )  Entry of glucose to cells A) Facilitated diffusion transport system (GLUT4)  Entry of glucose to cells B) ATP-dependent Na+- monosaccharide cotransport system This is an energy-requiring process that transports glucose “against” a concentration gradient The movement of glucose is coupled to the concentration gradient of Na+, which is transported into the cell at the same time, called sodium-dependent glucose transporter (SGLT). This type of transport occurs in : ❑ The epithelial cells of the intestine ❑ Renal tubules ❑ Choroid plexus (part of the blood–brain barrier) IV OVERVIEW OF METABOLISM  Overview of Metabolism Metabolism: is the sum of all the chemical changes occurring in a cell, a tissue, or the body. Most pathways can be classified as either catabolic (degradative) or anabolic (synthetic). Catabolic reactions Anabolic reactions Capture chemical energy in the form of ATP from Combine small molecules, such as amino acids, to the degradation of energy-rich fuel molecules form complex molecules such as proteins Allows molecules in the diet (or nutrient molecules Require energy (are endergonic), which is generally stored in cells) to be converted into building blocks provided by the hydrolysis of ATP needed for the synthesis of complex molecules. Involve chemical reductions by the electron donor NADPH (eg fatty acid synthesis) Overview of Metabolism Overview of Carbohydrates Metabolism  Fate of dietary glucose Starch, glycogen, sucrose, lactose Glu (6C) Fatty acids ATP adipose tissue Glucose is the Storage of energy Glycogen primary source of energy liver and muscles Storage of energy