CHAPTER 5: MICROBIAL METABOLISM _____________: sum of all the ________________ in an organism that are necessary to maintain life !! Harvesting _______ Converting ______ to ATP Synthesing new compounds ORGANIC COMPOUNDS DEGRADATION BY CHEMOHETEROTROPHS Metabolic Diversity Among Organisms NUTRITIONAL TYPE ENERGY SOURCE CARBON SOURCE EXAMPLE _______________TROPH Light ________ Oxygenic: Cyanobacteria, plants, algae. Anoxygenic: Green, purple bacteria. CHEMOAUTOTROPH Chemical CO2 Hydrogen, Sulfur, Nitrogen, Iron-oxidizing bacteria. PHOTOHETEROTROPH Light Organic compounds Green, purple nonsulfur bacteria. CHEMOHETEROTROPH Chemical ____________ compounds Fermentative bacteria. Animals, protozoa, fungi, bacteria. Metabolic Reactions Two Main Categories of Chemical Reactions: _________ – larger molecules are broken down; energy releasing process-exergonic _________ – larger molecules are made from smaller ones; energy requiring process-endergonic Catabolic reactions provide the _______ for anabolic reactions. The Generation of _________ PHOSPHORYLATION of ADP. 1. ___________ PHOSPHORYLATION- the transfer of a high-energy PO4- to ADP. 2. _________ - energy released from the transfer(loss) of electrons (oxidation) from one compound to another (reduction) is used to generate a proton gradient which is then used to make ATP 3. PHOTOPHOSPHORYLATION – sunlight causes chlorophyll to give up electrons. Energy released from the transfer of electrons (oxidation) of chlorophyll through a system of carrier molecules is used to generate ATP _____________ Phosphorylation THE ROLE OF ___________ ANABOLIC AND CATABOLIC REACTIONS Key Factors Involved in Energy Production 1._________ REACTIONS • Transfer electrons from one substrate to another • When electrons are removed protons follow • Oxidation – removal, ___ of electrons • Reduction – _______ of electrons Coupled 2. ELECTRON CARRIERS • Carry electrons • Reduced electron carriers have reducing power • Their bonds contain usable __________ 3. ENZYMES - catalysts Oxidation-Reduction Reactions in chemical reactions • OXIDATION - removal of electrons; energy _______ • REDUCTION - gain of electrons; energy ________ • REDOX REACTION - an oxidation reaction paired with a reduction reaction. Figure 5.9 Oxidation-Reduction Reactions in ____________ systems The electrons are often associated with hydrogen atoms. Biological oxidations are often dehydrogenations. Figure 5.10 Electron _________* note error on slide Catabolic Mechanisms of Generating Energy from ______ 1. CELLULAR RESPIRATION Chemical reactions that generate energy from the breakdown of complex organic compounds compounds; 2 2 2 NADH can occur aerobically or anaerobically 2 the final electron acceptor is an __________ compound. 2. _________________ Anaerobic reactions that generate energy from the break down of complex organic compounds the final electron acceptor is an __________ compound. 6 4 FADH2 6 2 4 Cellular Respiration: the chemical process by which compounds are broken down to release energy and that energy is used to make ATP ANAEROBIC RESPIRATION ___________ RESPIRATION • O2 _____ required • O2 __________ • Relatively ______ amount of energy is released • Relatively large amount of energy is released • Final electron acceptors • ____is final electron acceptor • ________ compounds (other than oxygen) • Nitrate ions (NO3 -) • Sulfate ions (SO42-) • Carbonate ions (CO32-) Ex. C6H12O6 6CO2 + 6H2O + Energy Aerobic Respiration Carbohydrate ___________ the breakdown of carbohydrates to release energy PROPERTIES • ATP generating process • Redox reactions • O2 final electron acceptor 4 MAJOR STEPS 1. _______ of Glucose -___________ -Pentose Phosphate Pathway -Entner-Doudoroff Pathway 2. Preparatory/Transition Step 3. Krebs cycle 4. Electron transport chain ____________ • __________ of glucose to 2 pyruvic acid, • produces 4 ATP (2 ATP net), 2 NADH + 2H+ Oxidation • occurs in cytoplasm Glucose + 2 ATP + 4 ADP + 4 PO4– + 2 NAD+ 2 pyruvic acid (pyruvate) + 4 ATP (2ATP net) + 2 NADH + 2H+ Preparatory stage: __________ Glucose is split to form two molecules of glyceraldehyde 3phosphate Energy conserving stage: The two glyceraldehyde 3phosphate molecules are _____ to 2 pyruvic acid molecules ________are produced 2 NADH are produced Glyceraldehyde3-Phosphate (x2) Transition/Intermediate Step • ________ acid (from glycolysis) is: 1. _____________ 2. decarboyxlated Produces Acetyl CoA + NADH +H+ + CO2 Figure 5.13.1 Krebs Cycle/TCA Cycle/Citric Acid Cycle Figure 5.13.2 Krebs Cycle (_____ per _______ molecule) Acetyl CoA(2C) + oxaloacetic acid(4C) Citric acid (6C) _________ of citric acid(citrate) produces 3NADH and 1FADH2 • Large energy yield • Generates high energy ___________ • High energy electrons from citrate are transferred to energy carriers NAD+ and FAD, which become reduced to NADH and FADH2 (2x)Citric acid(6C) → Oxaloacetic acid(4C) + 6 NADH 2 FADH2 4 CO2 Contain most of energy in ______ molecule H+ (protons) 2 ATP (substrate level phosphorylation) Eukaryotes – mitochondrial matrix; Prokaryotes - ___________ _______________ ____ synthesis using an Electron Transport Chain The other H+ and electrons (plus the energy in the electrons) are transferred to O2 4H+ + 4e- + O2 → 2H20 Final electron acceptor Figure 5.16.2 The Electron Transport Chain: a series of carrier molecules that are, in turn, _________ and ________ as electrons are passed down the chain. • Carrier Molecules: flavoproteins, cytochromes, ubiquinones. • As electrons are transferred, energy is released: • Some energy used to pump some of the protons across mitochondrial membrane (plasma membrane) in prokaryotes. _____ concentration builds up on one side of membrane – creates electrochemical gradient. • Energy released can be used to produce ____ by chemiosmosis. ___________ Force • Protons diffuse across membrane through special ___________ • Channels contain ATP synthase • Proton motive force drives synthesis of ATP from ADP using ATP synthase ATP Synthase ADP + Pi → ATP H+ CHEMIOSMOSIS-_______ _________ generates ATP Summary of __________ Respiration in _____karyotes Energy Tally • Energy produced from complete oxidation of 1 glucose using aerobic respiration PATHWAY GLYCOLYSIS INTERMEDIATE STEP KREBS CYCLE TOTAL ATP PRODUCED NADH _______ PRODUCED PRODUCED 2 2 0 0 2 0 2 ___ 2 4 10 2 ATP Tally in Prokaryotes Energy produced from the complete oxidation of 1 glucose in aerobic respiration *only 36 ATP are produced in eukaryotes PATHWAY SUBSTRATE-LEVEL PHOSPHORYLATION GLYCOLYSIS INTERMEDIATE STEP KREBS CYCLE 2 TOTAL ________________________ PHOSPHORYLATION From NADH From FADH2 6 0 0 6 0 2 ____ 4 4 30 4 Fermentation Pathways Fermentation and End Product Diversity The enzymatic breakdown of carbohydrates where final electron acceptor is an __________ molecule Oxidation of glucose releases small amounts of ATP Glucose __________ to pyruvate + 2 ATP produced Pyruvate _________ to fermentation end products O2 not required, therefore an anaerobic process ______________ not required Final electron acceptor-organic molecule Comparison of ________ and Alcoholic Fermentation Bacterial Fermentation Figure 5.23 Comparison of Cellular ___________ and Fermentation _________ Pathways, Pathways of Synthesis 1) Simple mono- and disaccharides → polysaccharides Ex.: Glycogen-energy storage Peptidoglycan Cell wall 2) Glycerol and fatty acids → lipids 3) Amino acids from glucose metabolism → __________ 4) Glucose → ribose sugars of nucleotides Pentose-phosphate pathway Entner-Doudoroff pathway _______ of Organic Food Molecules _____________ Pathways metabolic pathways that have both catabolic and anabolic functions Figure 5.32.1 Biochemical Assays • Used to identify bacteria. ___________ Key Figure 10.8 Enzymes • BIOLOGICAL CATALYSTS – speed rate of reaction • __________ for a chemical reaction; not used up in that reaction • STRUCTURE 1. _____enzyme: protein component of enzyme 2. Cofactor: Non_________ component • _______enzyme: Apoenzyme + cofactor __________ Activity Factors Influencing ______ Activity TEMPERATURE pH Substrate concentration Figure 5.5a Factors Influencing Enzyme Activity Enzymes can be denatured by __________ and _____ Figure 5.6