Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Metalloprotein wikipedia , lookup
Evolution of metal ions in biological systems wikipedia , lookup
Cofactor engineering wikipedia , lookup
Photosynthesis wikipedia , lookup
Nicotinamide adenine dinucleotide wikipedia , lookup
Adenosine triphosphate wikipedia , lookup
Biochemistry wikipedia , lookup
Metabolism • A cell is a miniature factory • A large number of Chemical reactions are occurring • A (reactants) + B (reactants) ----> C (products) • Chemical reactions are either endogonic (req. energy) or exogonic (release energy) Enzyme • Reduce Activation energy • Contain specific active sites • Substrates bind to active sites, forming the enzyme-substrate complex. • Enzyme-substrate interaction results in product formation • For ex. A + B ---> C Enzymes • Two types of enzyme-substrate inhibition • 1.) Competitive – different substrates bind to the same active site. • 2.) Allosteric – substrates cause the protein to change 3-D shape. Thus, the function changes. Electron transfer • Oxidation – when electrons are given up (donation) • Reduction – when electrons are taken in (accepting) Metabolism Catabolism - produce energy (ATP) - breakdown molecules (ex. glycolysis) Anabolism - use energy (ATP) - synthesize macromolecules (ex. DNA, lipids, etc.) Metabolic Strategies All are based on energy, electron and carbon source: 1.) Chemoorganotrophic (chemoheterotroph) 2.) Chemolithotrophic (chemoautotroph) 3.) Photolithotrophic (photoautotroph) 4.) Photoorganotrophic (photoheterotroph) Metabolism Large molecules Catabolism Anabolism Energy (ATP) Small molecules (precursors) Catabolism - ex. Glycolytic pathway (glycolysis) - Two types of catabolism: 1.) respiration-aerobic( w/ oxygen) - anaerobic respiration (w/o oxygen) 2.) fermentation (does not use oxygen) - Glucose is taken in and broken down in order to generate energy and to use the glucose carbons as a source of carbon. Glycolysis Respiration Glycolysis Fermentation TCA Cycle Organic products Oxidative phosphorylation Respiration - Three phases - 1.) Glycolysis - 2.) TCA cycle - 3.) oxidative phosphorylation Fermentation - Two phases - 1.) Glycolysis - 2.) Fermentation -high yield of product, ex. ethanol Chemical reaction • Metabolism involves chemical reactions A+B-->C+D, ex. Glycolysis • Three events – 1.) electron flow – 2.) carbon flow – 3.) energy production Metabolism Flow of electrons carbon Metabolism Binary fission energy Electron flow eNAD NADH Coenzymes NAD-->NADH Coenzyme NAD -->NADH NADH NAD TCA eNADH->NAD electrons NADH H2O O2 Oxidative phosphorylation (electron transport chain) Fermentation Reduction/oxidation (redox) - Electron flow involves redox reactions. - Reduction - a molecule accepts an electron. Reduced. Ex. NADH - Oxidation - a molecule donates an electron. Oxidized. Ex. NAD - H ion transfer is usually accompanied by electron transfer. Reduction/Oxidation (Redox) • Molecules involved in redox reactions • Ex. Coenzymes: (oxidized)NAD+ + H+ + e- --> NADH (reduced) Occurs in glycolysis, TCA • Ex. Electron transport chain (electron carriers accept electrons from NADH) • Ex. 1/2O2 + H2 + e- ---> H2O Final electron acceptor can be oxygen, sulfate, nitrate, carbonate. (S,N, and C are anaerobic respiration) • Cycling : If both fermentation and respiration are possible, the reduced NADHs are used in the electron transport systems and fermentation. The oxidized NADs are used in respiration and/or fermention. Glycolysis Respiration Fermentation NADH NAD NADH TCA Cycle NADH NAD NADH H2O Electron transport chain (chemiosmosis) Organic products Carbon Flow Glucose (6 C molecule) Intermediates Biosynthesis (anabolism) Pyruvic acid (Two 3 C molecule) TCA Intermediates (3 or2 C) CO2 Glycolysis (Breakdown of glucose) Glycolysis Respiration Fermentation NADH Pyruvic acid NADH TCA Cycle NADH CO2 H2O Electron transport chain (chemiosmosis) Organic products Carbon flow • Large molecules are broken into smaller molecules (catabolism) • Critical intermediates are generated (ex. Pyruvic acid, etc.) They are used in the anabolism process as well as entry back into the catabolism process. Energy Production • 1.) Substrate-level phosphorylation+ P ==> ATP (associated with glycolysis) ADP • 2.) Oxidative phosphorylation Ex. electron transport chain associated with the proton motive force. • 3.) Photophosphorylation – converts light energy to chemical energy of ATP and NADPH. (Light +carbon dioxide+wate =>sugar=>glycolysis) Substrate Level Phosphorylation - Occurs at certain steps in glycolysis - Fermentation generates most of its ATP using this process since no oxidative phosphorylation is present. - Level of ATP generation is less than oxidative phosphorylation. - Fermentation:Makes up difference by metabolizing large amounts of material, thus generating large amounts of product. Oxidative Phosphorylation - Electron transport chain - Located in the cytoplasmic membrane - Transfer of electrons also exports H ions to one side of the membrane, creating a gradient (Proton motive force). -The H ions re-enter thru an ATPase, generating high levels of ATP. This process is call chemiosmosis Photophosphorylation • Light trapping pigments (chlorophylls) • Sugars are synthesized with energy from light. • The sugars are then metabolized (glycolysis). Glycolysis Glucose Respiration Fermentation NADH ATP ATP Pyruvic acid TCA Cycle CO2 ATP FADH2 NADH H2O ATP Electron transport chain (chemiosmosis) Organic products Respiratory Metabolism • Conversion of carbohydrates to pyuvate – end of glycolysis (EM pathway) • Oxygen is the final electron acceptor => water • Includes the TCA cycle • Includes Oxidative phosphorylation Summary of Glycolysis (EM) • Transfer electrons (oxidation-reduction) • Generates NADH (oxidized) • Generates small amounts of ATP (substrate level phosphosphorylation), compared to the oxidative phosphorylation. • Generates critical intermediates Summary of TCA • Generates critical intermediates • Generates oxidized coenzymes (NADH, FADH2) • Release carbon dioxide (reduces size of molecule) Summary of ETS (oxidative phosphorylation) • Accept electrons from oxidized coenzymes • Electron carriers transfer electrons to other carriers. • Transfer H ions to one side of cytoplasmic membrane (a gradient is formed) • H ions move back into cytoplasm by way of the ATPase. Thus, ATP is generated in large amounts. Alternate Glycolytic Pathway • To supply coenzymes, critical intermediates, etc., during times of adaptation, absence of EM; other pathways are needed. • Entner-Doudoroff pathway - aerobic bacteria (lack an EM enzyme), certain Archaea • Less ATP generated • Generates NADPH, rather than NADH Alternate Glycolytic Pathway • • • • Modified ED pathway Partially nonphosphorylated Some Archaea (Halo, Thermo), Eubacteria Less to no net production of ATP, compared to EM. Alternate to glycolysis • Methylglyoxal pathway • Eubacteria - during low phosphate concentrations. • Less ATP generated, compared to EM. Pentose Phosphate Pathway • Directly linked to EM or glycolysis • Major role is to generate ribose for the biosynthesis (anabolism) of DNA, RNA, ATP NAD, NADP. • Normal process (operates in conjunction with EM) Glycolysis supplies energy for anabolism Glucose Respiration Fermentation NADH ATP ATP Pyruvic acid TCA Cycle CO2 ATP NADH H2O ATP Electron transport chain (chemiosmosis) Organic products Metabolism Large molecules Catabolism Anabolism Energy (ATP) Small molecules (precursors) Review Metabolism • Shared with both respiration and fermentation • Three phases of glycolytic pathway 1.) glycolysis 2.) TCA 3.) electron transport chain (oxidative phosphorylation) • Three events during catabolism 1.)electron flow 2.)carbon flow 3.)energy production Review continued • 1.) Redox reactions • Depends on reduction potential, positive value- more likely to accept electron. • Participating molecules ex. NAD, NADH (electron donors or acceptors) • 2.) 6C molecule to two 3C molecules • C molecules (intermediates) enter biosynthesis or is released as CO2 Review continued • 3.) Three forms 1.) substrate level phosphorylation 2.) oxidative phosphorylation 3.) photophosphorylation • Alternate forms of the glycolytic pathway exist in order to supply coenzymes, ATP, etc. Fermentation • Variety of products are synthsized. • Use products to identify specific microoganim. • Ex. Lactic acid, Ethanolic, Propionic Acid, Mixed Acid, Butanediol, Butyric acid, Amino acid, Acetic to methane • Electron donor (substrate) and acceptor (product) are internal of the cell, thus less energy generated. Mixed acid fermentation • Methyl Red test - pH based test for acid production. • Clinical labs use it to identify E. coli, urinary tract infections, etc. • NADH is reoxidized to NAD Butanediol fermentation • Enterobacter, Serratia, Klebsiellaassociated with opportunistic infections. • Voges-Proskauer test - detects an intermediate metabolite. • Used with MR test ex. VP-MR test • Testing water supplies • E.coli VP(-)MR(+), EnterbacterVP(+)MR(-) Photoautotrophy • Absorption of light energy • Oxygenic photosynthesis- algae, cyanobacteria, release oxygen, two photosystems exist • Anoxygenic photosynthesis-Green and purple bacteria, no O is released, one photosystem