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Unit Bioenergetics A. 1. 2. 3. 4. 5. Cellular Energy Uses of cellular energy (ATP) build molecules & maintain structure transport materials move & grow reproduce The products of cellular respiration are the reactants of photosynthesis. B. What is ATP? 1. Adenosine tri-phosphate – phosphate sugarribose, nitrogen base -adenine 2. Energy is released for cell usage when a phosphate group is removed. This produces ADP (di-phosphate) and AMP (monophosphate) low energy If ATP is a fully charged battery, ADP would be half charged and AMP would be nearly out of energy Phosphorylation - the metabolic process of introducing a phosphate group into an organic molecule. Enzymes activated or deactivated II. Respiration A. Breathing “respiration” vs. cellular respiration Respiration – breathing, an exchange of gases between organism and environment Cellular respiration – aerobic harvesting of energy from food molecules B. Cellular respiration – balanced equation C6H12O6 + 6 O2 Glucose energy 6 CO2 + 6 H2O + 38 ATP 40% of the energy from glucose is used in the cells 60% of the energy is lost as heat C. Oxidation/Reduction “Redox” reactions – always occur together It’s the major source of energy along with the sun leo says ger Oxidation – loss of electrons (H atoms) from one molecule oxidized if 1 or more electrons are lost cellular respiration: glucose oxidized – loses H Reduction – addition of electrons (H atoms) to a molecule reduced if 1 or more electrons are gained cellular respiration: O2 gas reduced – gains H Fig. 9-UN3 becomes oxidized becomes reduced electron transport chain – series of redox reactions that pass e- from carrier to carrier a) NADH & FADH2 are electron carriers Fig. 9-13 NADH 50 2 e– NAD+ FADH2 2 e– 40 FMN FAD Multiprotein complexes FAD Fe•S Fe•S Q Cyt b 30 Fe•S Cyt c1 I V Cyt c Cyt a Cyt a3 20 10 2 e– (from NADH or FADH2) 0 2 H+ + 1/2 O2 H2O Overview of the stages of cellular respiration Glycolysis – “splitting of sugar”, glucose is broken into 2 molecules of pyruvate through 9 different chemical reactions Occurs in the cytoplasm; anaerobic Net of 2 ATP produced by substrate-level phosphorylation (-2 ATP + 4 ATP) 2 NAD+ are reduced to 2 NADH for electron transport chain Fig. 9-8 Energy investment phase Glucose 2 ADP + 2 P 2 ATP used 4 ATP formed Energy payoff phase 4 ADP + 4 P 2 NAD+ + 4 e– + 4 H+ 2 NADH + 2 H+ 2 Pyruvate + 2 H2O Net Glucose 4 ATP formed – 2 ATP used 2 NAD+ + 4 e– + 4 H+ 2 Pyruvate + 2 H2O 2 ATP 2 NADH + 2 H+ Citric Acid (Kreb’s) Cycle – creates CO2 from pyruvate 2 molecules of pyruvate become 2 molecules of acetyl CoA, which enters the citric acid cycle Energy yield is 2 ATP, 6 NADH & 2 FADH2 Provides electrons for respiration Fig. 9-11 Pyruvate CO2 NAD+ CoA NADH + H+ Acetyl CoA CoA CoA Citric acid cycle FADH2 2 CO2 3 NAD+ 3 NADH FAD + 3 H+ ADP + P i ATP Fig. 9-12-8 Acetyl CoA CoA—SH NADH +H+ H2O 1 NAD+ 8 Oxaloacetate 2 Malate Citrate Isocitrate NAD+ Citric acid cycle 7 H2O NADH + H+ 3 CO2 Fumarate CoA—SH 6 -Ketoglutarate 4 CoA—SH 5 FADH2 NAD+ FAD Succinate GTP GDP ADP ATP Pi Succinyl CoA NADH + H+ CO2 Oxidative Phosphorylation – phosphorylates ADP to produce ATP (34) Electron transport chain – pumps H+ ions across membrane as electrons are transported Takes place within inner membrane of mitochondria Small amounts of energy released – produces ATP Chemiosmosis – potential energy of the electrochemical gradient drives the diffusion of H+ ions through ATP synthase ( enzyme) producing molecules of ATP Oxygen acts as the final electron acceptor, it bonds with 2 H+ ions to create water ETC Fig. 9-14 INTERMEMBRANE SPACE H+ Stator Rotor Internal rod Catalytic knob ADP + P i ATP MITOCHONDRIAL MATRIX Fermentation Anaerobic process – cells are starved of oxygen strict anaerobes are poisoned by oxygen facultative anaerobes can survive with or without O2 2 ATP produced by glycolysis, 0 ATP from fermentation Animals – lactic acid produced, causes sore muscles Bacteria – fermentation used to make cheese, yogurt, soy sauce & sauerkraut Yeast – alcohol fermentation Fig. 9-18b 2 ADP + 2 P i Glucose 2 ATP Glycolysis 2 NAD+ 2 NADH + 2 H+ 2 Pyruvate 2 Lactate (b) Lactic acid fermentation Fig. 9-18a 2 ADP + 2 P i Glucose 2 ATP Glycolysis 2 Pyruvate 2 NAD+ 2 Ethanol (a) Alcohol fermentation 2 NADH + 2 H+ 2 CO2 2 Acetaldehyde The End … IV. Photosynthesis A. Autotrophs – “self-feeders”, make own food from inorganic matter 1.Photoautotrophs – make energy from sunlight through photosynthesis Examples: plants, bacteria, algae, & certain protists B. Photosynthesis – balanced equation 6 CO2 + 6 H2O + sunlight -------- C6H12O6 + 6 O2 Carbon water glucose oxygen dioxide gas • Photosynthesis Facts • Takes place in the mesophyll (green tissue) of plant leaves which contain many chloroplasts – Stroma – thick fluid in chloroplast where sugars are made – Thylakoids – membrane sacs that hold pigments • Pigments trap energy from sunlight – carotene – orange / red – chlorophyll – green – xanthophyll - yellow – Grana – concentrated stacks of thylakoid membrane – Stomata – pores that allow CO2 in & O2 out • • • • – Chemical reactions of Photosynthesis - Redox 1. Light reactions – O2 gas is produced by the splitting of water a. Occurs in the thylakoid membrane c. Steps that absorb solar energy and store it as chemical energy in ATP and NADPH, which power the dark reactions • • • • Stages Photosystem II – absorbs energy from sunlight, excites electrons – P680 – absorbs red light (680 nm) best – P700 – absorbs red light (700 nm) best – – transport protein contains enzyme ATP synthase powers the creation of ATP from ADP Electron transport chain – carrier molecules pass along electrons; H+ atoms pumped across membrane Photosystem I – absorbs more photons of energy; NADP+ & H+ produced NADPH H+ ions move across the membrane by facilitated diffusion • Dark reactions – glucose is created from CO2 and water – Occurs in the stroma – Often called the Calvin Cycle – Uses the enzyme rubisco