Metabolism: Lecture Notes PDF

METABOLISM Prepared by: Prof. Nancy D. Buzon Natural Science Dept. METABOLISM LEARNING OUTCOMES At the end of the module the student should be able to: Explain what metabolism is. Understand the different intermediate compound in...

METABOLISM Prepared by: Prof. Nancy D. Buzon Natural Science Dept. METABOLISM LEARNING OUTCOMES At the end of the module the student should be able to: Explain what metabolism is. Understand the different intermediate compound in metabolic Pathways. Describe the glycolysis and KREB’s cycles. Interpret the Integrated Metabolic Pathway. METABOLISM Is the sum total of all biochemical reactions that take place in a living organism. Two Subtypes of Metabolic Reactions CATABOLISM – metabolic reactions in w/c large biochemical molecules are broken down to smaller ones. Usually releases energy. ANABOLISM – metabolic reactions in w/c small biochemical molecules are joined together to form larger ones. Usually require energy in order to proceed. Exercise 1. Classify by writing A – anabolic and B – if catabolic 1. Synthesis of polysaccharide from monosaccharides 2. Formation of nucleic acid from nucleotides. 3. Hydrolysis of pentasaccharide to monosaccharides. 4. Hydrolysis of triacylglycerol to glycerol & fatty acid 5. Synthesis of protein from amino acids. 6. Hydrolysis of starch to maltose. Important Intermediate Compounds in Metabolic Pathways 1. Adenosine phosphates : AMP, ADP, ATP phosphate-ribose -adenine AMP phosphate-phosphate-ribose-adenine ADP Phosphate-phosphate-phosphate-ribose-adenine ATP ATP + H2O  ADP + Pi + energy ADP + H2O  AMP + Pi + energy ATP + 2H2O  AMP + 2Pi + energy Bonds to remember !!!! Phosphoanhydride bond – is the chem bond formed when two phosphate groups react with each other and water is produced. Phosphoester bond - is the chem. Bond between a phosphate group and a sugar. Important Intermediate Compounds in Metabolic Pathways 2. Flavin Adenine Dinucleotide, FAD > a coenzyme required in numerous metabolic REDOX reactions. > Source: Riboflavin > active portion is flavin > FAD – oxidized form; is an oxidizing agent FADH2 - reduced form Structure of FAD Important Intermediate Compounds in Metabolic Pathways 3. Nicotinamide Adenine Dinucleotide, NAD > is a coenzyme > source: niacin > active portion is nicotinamide > oxidizing agent > NAD – oxidized form NADH - reduced form Structure of NAD NAD IN OXIDIZED AND REDUCED FORM Important Intermediate Compounds in Metabolic Pathways 4. Coenzyme A (CoA-SH) > source: pantothenic acid > active portion - SH group > Coenzyme A is a major cofactor which is used to transfer a two carbon unit commonly referred to as the acetyl group. CoA-SH Acetyl CoA The acetyl group (CH3C=O) is attached to the sulfur of the CoA through a thiol ester type bond. Acetyl CoA is important in the breakdown of fatty acids and is a starting point in the citric acid cycle. Acetyl CoA BONDS TO REMEMBER O ║ CH3 - C - S - CoA ↑ thioester bond GLYCOLYSIS Is the metabolic pathway by which glucose, a carbon six molecule is converted into two molecules of pyruvate, a C3 molecule; chemical energy in the form of ATP is produced and NADH –reduced coenzymes are produced. METABOLIC PATHWAYS 1. ANAEROBIC pathway – is an oxidation process in w/c no molecular oxygen is utilized in the conversion of glucose to pyruvate. OA = NAD 2. AEROBIC pathway – pathways that require molecular oxygen. ***GLYCOLYSIS is an anaerobic pathway… GLYCOLYSIS Is a ten-step process, every step is enzyme- catalyzed. Two stages: (1) steps 1 to 3… six carbon stage (2) steps 4 to10 ….three carbon stage ALL ENZYMES needed for glycolysis are present in the cell cytosol, w/c is where glycolysis takes place. Steps in Glycolysis 1. Phosphorylation - hexokinase 2. Isomerization - phosphoglucoisomerase 3. Phosphorylation – phosphofructokinase 4. Cleavage – aldolase 5. Isomerization – triosphosphate isomerase 6. Oxidation and Phosphorylation – glyceraldehyde-3-phosphate dehydrogenase Steps in Glycolysis 7. Phosphorylation of ADP – phosphoglycerokinase 8. Isomerization - phosphoglyceromutase 9. Dehydration – enolase 10. Phosphorylation of ADP – pyruvate kinase Glucose + 2NAD+ + 2ADP + 2Pi  2 pyruvate + 2NADH + 2ATP + 2H+ + 2H20 KREB’S CYCLE Citric Acid Cycle Tricarboxylic acid cycle Is the series of biochemical reactions in w/c the acetyl portion of acetyl CoA is oxidized to CO2 and the reduced coenzymes FADH2 and NADH are produced. Takes place in the mitochondria Entry: acetyl CoA  Pyruvate + Acetyl CoA Produces CO2 by action of NAD+ Acetyl CoA enters the In the Citrate All compounds are tricarboxylic acid C from glucose are in red C from glucose are as CO2 (decarboxylation) Several NADH +H+ are generated via oxidation of intermediates HYDROXYMETABOLITE Metabolism Summary  INTEGRATED METABOLIC PATHWAYS GLYCOLYSIS KREB’S CYCLE OXIDATIVE PHOSPHORYLATION GLUCOSE GLYCOGEN Fatty Acyl CoA Fatty acid Phosphoglucomutase Phosphorylase O ATP + Mg++ ATP + Mg++ ʻ gal,man GLUCOSE-6P GLUCOSE – 1 - P CH3C-S-CoA NAD Pentose Phosphohexose isomerase ATP Citrate ADP +P1 FRUCTOSE-6-P oxaloacetate FDd Phosphofructokinase cis-aconitate ATP + Mg++ NAD CoQ FRUCTOSE 1-6-di-P isocitrate malate Cyt b Triose phosphate (G3P) NAD (NADP) ATP DHAP 3-GLYCERALDEHYDE fumarate ADP + P1 Isomerase PHOSPHATE oxalosuccinate Cyt C1 (G3P) FAD succinate alpha ketoglutarate Cyt C Dehydrogenase NAD GDPpi NAD NADH Succinyl CoA Cyt ata3 1,3 diphosphoglycerate ATP phosphoglycerate ADP + P1 kinase GTP O2 3 phosphoglycerate phosphoglycerate FPs mutase 2 phosphoglycerate α-glycerophosphate shuttle (E-FAD) enolase phosphoenolpyruvate (PEP) pyruvate ADP kinase ATP pyruvate aa: cys, ser, thr pyruvate Asp, Asn oxaloacetate (LAD) NADH ile, leu, trp acetyl-CoA Tyr, phe fumarate Lactic Acid phe, tyr, leu, lys, trp acetoacetyl-CoA to Acetyl CoA ile, met, val succinyl CoA Dehydrogenase lactate Thank you for Listening…