Introduction to Metabolism Lecture Notes PDF

Introduction to METABOLISM  Metabolism is the sum of all chemical changes occurring in a cell , tissue or the body It is composed of metabolic pathways Pathway: is a multistep sequence of reactions in which the product of one reaction serves as the substrate of the...

Introduction to METABOLISM  Metabolism is the sum of all chemical changes occurring in a cell , tissue or the body It is composed of metabolic pathways Pathway: is a multistep sequence of reactions in which the product of one reaction serves as the substrate of the subsequent reaction Each reaction is catalyzed by a specific enzyme. A B C D E F 1 2 3 4 5 6 Different pathways can intersect forming a network of chemical reactions (Map). K T A B C D E Pathways can be classified as either : L U catabolic (degredative) or anabolic (synthetic) M V Or amphibolic (dual = both anabolic and catabolic) Krebs cycle is mainly a catabolic cycle, but with some anabolic features. e.g. part of Krebs cycle is used for the synthesis of glucose from amino acids Metabolic map is a map that shows components of a pathways of metabolism  Catabolic & Anabolic Reactions Catabolic Reactions Anabolic Reactions Catabolicreactions break Anabolic pathways down complex molecules form complex end such as proteins, products from simple polysaccharides and lipids precursors to few simple molecules i.e. synthesis of Serve to: yield energy glycogen from glucose in the form of ATP from & proteins from amino the degradation of energy- acids rich fuel molecules  Stages of Catabolism Citric acid cycle produces NADH & FADH2 Electrons flow from NADH & FADH2 in the mitochondria (electron transport chain) generates energy in the form of ATP (oxidative phosphorylation).  Adenosine triphosphate ATP (carrier of energy) Hydrolysis of the end phosphate group forms adenosine diphosphate [ATP -> ADP + Pi] and releases 7.3 kcal of energy per mole of ATP ATP powers cellular work: A cell does three main kinds of work: – Mechanical work, contraction of muscle cells – Transport work, pumping substances across membranes – Chemical work, driving endergonic reactions such as the synthesis of polymers from monomers  Mitochondria BATTERY OF THE CELL site for generating ATP Through Electron Transport Chain & Oxidative Phosphorylation  In Electron Transport Chain in the mitochondria Flow of electrons from NADH & FADH2 (through electron carriers CoQ & cytochromes) to oxygen yields energy This energy is used for phosphorylation of ADP to ATP (phosphorylation) Oxidative Phosphorylation (in mitochondria) Oxidation: electron flow in electron transport chain (with production of energy) Phosphorylation: phosphorylation of ADP to ATP  Diet Carbohydrates Glycogen (liver & Sk. Ms.) Glucose GLYCOLYSIS (in cytoplasm) Lactate Pyruvate in mitochondria Acetyl CoA CATABOLISM OF Citric Acid Cycle CARBOHYDRATES (in mitochondria) NADH & FADH2 Electron transport chain (flow of electrons) Formation of ATP (oxidative phosphorylation)  Triglycerides Fatty acids Lipid Catabolism Acetyl CoA Citric acid cycle ATP Energy  Protein Catabolism Protein Amino Acid amino group DEAMINATION (a-ketoacid) (nitrogen) (carbon skeleton) incorporated into other excreted catabolised synthesis Compounds of other compounds (e.g. urea) acetyl CoA Citric Acid Cycle ATP (energy)