Metabolism_student.pptx

Metabolism AP 151  Metabolism All of the reactions in the body that require energy transfer = Can be divided into: 1) Anabolism: requires the input of energy to synthesize large molecules 2) Catabolism: releases energy by breaking...

Metabolism AP 151  Metabolism All of the reactions in the body that require energy transfer = Can be divided into: 1) Anabolism: requires the input of energy to synthesize large molecules 2) Catabolism: releases energy by breaking down large molecules into small molecules Catabolism Drives Anabolism a. The catabolic reactions that break down glucose, fatty acids, and amino acids serve as energy sources for the anabolism of ATP b. Involves many oxidation-reduction reactions c. Complete catabolism of glucose requires oxygen as the final electron acceptor d.Called aerobic cellular respiration e.Breaking down glucose requires many enzymatically catalyzed steps, the first of which are anaerobic  Metabolism Aerobic Respiration of Glucose Steps: 1. Glycolysis – occurs in the cytoplasm Anaerobic 2. Formation of Acetyl coenzyme A 3. Citric acid (Krebs) cycle – occurs in the matrix of the mitochondria; aerobic 4. Electron transport – occurs on cristae of mitochondria inner membrane Aerobic C6H12O6 + O2  6 CO2 + 6 H2O + ATP  Energy (ATP) in Metabolism Catabolism and anabolism are coupled by ATP ATP can be made 2 ways Substrate level phosphorylation Less ATP produced Oxidative phosphorylation Making ATP Electron transport chain (ETC) + Chemiosmosis Cells using enzymes to oxidize nutrients passing along electrons (chemical energy) in order to make ATP (adenosine triphosphate) Cellular Respiration + ATP Role of ATP in anabolism and catabolism Compare substrate-level phosphorylation and oxidative phosphorylation Describe the role of NAD+ and FAD in the generation of ATP Outline the reactions that comprise cellular respiration  ATP and Catabolism and Anabolism  Catabolism and anabolism are coupled by ATP How is ATP is Made? Substrate level phosphorylation metabolism reaction that results in the production of ATP or GTP by the transfer of a phosphate group from a substrate directly to ADP or GDP Occurs in glycolysis and Krebs cycle Transferring from a higher energy (whether phosphate group attached or not) into a lower energy product Oxidative phosphorylation is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing the chemical energy stored within the nutrients in order to produce adenosine triphosphate (ATP) electrons are passed from one molecule to another, and energy released in these electron transfers is used to form an electrochemical gradient Occurs in mitochondria and electron transport chain  Generation of ATP  2 ways  Substrate level phosphorylation  Oxidative phosphorylation Substrate Level Phosphorylation Oxidative Phosphorylati on Carry hydrogen atoms to the electron transport chain Transfer energy to generate ATP Cellular Respiration  Breakdown of nutrients to generate ATP in the presence of oxygen  Cellular respiration  Involves different reactions  Glycolysis  Formation of acetyl coenzyme A  Krebs cycle  Electron transport chain Overview of cellular metabolis m Glycolysis Carbohydrate Metabolism Fate, metabolism, and functions of carbohydrates  Carbohydrate Metabolism  Digestion catabolizes complex carbohydrates into monosaccharides, such as glucose, which are absorbed into the bloodstream.  In cells, glucose is then catabolized to produce ATP.  Reactions involved  Glycolysis  Formation of acetyl coenzyme A  Krebs cycle  Electron transport chain  Glycolysis 1st step in catabolism of glucose Occurs in the cytoplasm of the cell Glucose is split into two pyruvic acid molecules a.6-carbon sugar  2 molecules of 3-carbon pyruvic acid b.C6H12O6  2 molecules C3H4O3 Note loss of 4 hydrogen ions These were used to reduce 2 molecules of NAD a.2NAD + 4H+  2NADH + H+ (2NADH)  Glycolysis Net Energy Gain in Glycolysis a.Glycolysis is exergonic, so some energy is produced and used to drive the reaction ADP + Pi  ATP b.4 ATP are generated. c.Glucose requires activation at the beginning provided by 2 P i stripped from 2 ATP molecules. d.This phosphorylates the glucose so that it can not diffuse back through the plasma membrane e.Net gain in glycolysis = 2 ATP Reactants and Products of Glycolysis Glucose + 2 NAD + 2 ADP + 2 Pi  2 pyruvic acid + 2 NADH + 2 ATP Use and Expenditure of Energy in Glycolysis GLUT (transporters) (6) Bi-directional Glyceraldehy (1) Hexokinase (muscles) de 3 (substrates) phosphate Glucokinase (liver) Dehydrogena se (7) Phosphoglycerate kina (2) Phosphohexose Isomerase Reversible step (8) Phosphoglycerate mutase (9) Enolase Irreversible step (3) (10) Pyruvate Kinase (4) Aldolase (enzyme) Irreversible step (Isomerization) (4) Aldolase (5) Triose Phosphate Isomerase “Pyruvate”  (where Glycolysis occurs) Cytoplasm of the cell Glucose (starting substrate) 2 Pyruvates (end product) (Byproducts) 4 ATP 2 NADH Anaerobic (NO O2) Anaerobic (low or no oxygen) 2NADH  2 NAD+ Create Lactic acid Pyruvate Aerobic (O2) Lactic Acid 2 C molecule  Acetyl CoA Transition Step Lactate Dehydrogenase (enzyme) the liver (converted to glucose) or (make ATP) = Decrease (makes blood more acidic) (metabolic acidosis) Formation of Acetyl Coenzyme A 2 Pyruvates 2 CoA 2 acetyl Coa 2 CO2 Need Oxygen to enter the mitochondria Aerobic pathway Loses a Carbon (decarboxylation) Pulls off CO2 Pyruvate Dehydrogenase (Enzyme) Add CoEnzyme A Irreversible step Gains H+ Enters the Krebs Cycle (Acetyl CoA) Citric Cycle 4 CO2 (decarboxylation reaction - remove C+) 6 NADH 2 FADH2 2 ATP NADH + FADH = ETC  (2) Aconitase (enzyme) (1) Citrate Reversible pathway synthase 2 Cycles Pyruvate dehydrogenase complex (1) Combines since there 2 CO2 2 NADH Oxaloacetate + Acetyl CoA are 2 = Citric Acid (8) Malate Dehydrogenase Pyruvates Oxidative phosphorylation (7) Fumarase Oxidative phosphorylati Converted NAD+ Add water (Oxidative phosphorylation) Into NADH (4) Isocitrate (reversible (6) Succinate Dehydrogenase Dehydrogenase ) Loses Carbon ATP (-) “Decarboxylation” ADP (+) Ca++ (+) (mm to contract) Oxidative phosphorylati Succinyl CoA (-) Succinyl CoA (5) -Ketoglutarate NADH (-) Succinyl CoA Synthatase Ca++ (+) Substrate Phosphorylation Dehydrogenase Electron Transport Chain Krebs = 6 NADH Krebs = 2 FADH2 Krebs = 2 ATP Transition = 2 NADH Glycolysis = 2 NADH 18 + 4 + 2 + 6 + 6 = 36 ATP (aerobic) Glycolysis = 2 ATP (anaerobic)  Stator (ATP synthase) High energy and pumps H+ out Diffusion – High to low Takes the e- and Take the e- pass them passes them Complex I Cytochrome C Complex IV Co-Enzyme Q 2 2 Complex III 6 6 2 2 Complex II e- + ½ O2 = water Potential Energy binds to ADP + Pi = Chemiosmotic Theory = High C to Lo Oxidative Phosphorylation Electron Transport Chain 4 CO2 6 NADH 2 FADH2 2 ATP NADH + FADH From the Krebs Cylce  Take these electrons to the ETC NADH = 3 (ATP) H+ FADH2 = 2 (ATP) H+ Krebs = 6 NADH Krebs = 2 FADH2 Krebs = 2 ATP Transition Step = 2 NADH Glycolysis = 2 NADH 18 ATP + 4 ATP + 2 ATP + 6 ATP + 6 ATP = 36 ATP (aerobic) (Oxygen has to be present) Glycolysis = 2 ATP (anaerobic) TOTAL = 38 ATP Pathways Glucose, Fatty Acids, Amino Acids  Pathways of Amino Acid Metabolism Sources of amino acids include dietary proteins and breakdown of body proteins. Pools of amino acids are maintained in body proteins, amino acid derivatives, nucleotides, hormones, or creatine. A small amount of amino acids is excreted in the urine. Ammonia produced from amino groups can be excreted in the urine or reincorporated into new amino acids. Relationships Between the Pathways for the Metabolism of Protein, Carbohydrate (Glycogen), and Fat (Triglyceride)