Cellular Respiration Remember • 1. ETC is a series of Redox on a membrane used to create a  leading to PE. • 2. CHOs are made in photosynthesis Energy Coupling between Photosynthesis and Cellular Respiration Light energy ECOSYSTEM CO2 + H2O Photosynthesis in chloroplasts Cellular respiration in mitochondria Organic+ O molecules 2 ATP powers most cellular work Heat energy Cell Respiration is Catabolism • • • • • Use O2 to make ATP. With O2 energy is made in mitochondria Without O2 energy is made in cytoplasm - G because its catabolic and exergonic. There is free energy to do work. Catabolism • Process where molecules are broken down, and their energy is released. Two types. • Fermentation-partial degradation of sugars that occurs without the use of oxygen. (anerobic respiration) • Cellular respiration- most prevalent and efficient metabolic pathway. Oxygen is consumed as a reactant along with organic fuel. (aerobic respiration) Photosynthesis and Cellular Respiration chemical reactions (Remember… conservation of matter.) 6 CO2 + 6 H2O C6H12O6 + 6 O2 + Heat Photosynthesis C6H12O6 + 6O2 6CO2 + 6H2O + Heat + Free E Cellular Respiration ATP Structure Cell Respiration has 3 steps • 1. Glycolysis • 2. Kreb’s Cycle or CAC • 3. ETC aka Oxidative Phosphorylation aka Chemiosmosis Glycolysis • Occurs in cytosol • This process occurs with/ without O2 in the cytolasm. • All organisms can do this…evolution…life before O2. • Glycolysis Animation • Better Glycolysis Animation Glycolysis Step-by-Step • 1. Start with a 6C hexose sugar. • 2. 2 PO4 are added to glucose using up 2ATP creating a 6C sugar diphosphate +2ADP. • 3. 6C sugar splits into 2 G3P molecules. • 4. NAD+ (e- carrier) adds PO4, removes a H+ from the 3C sugar and turns into NADH . The 2 G3P sugars turn into 2 3C sugars called pyruvate by the removal of both phosphates. • 5. Each 3C sugar yields 2ATP when converted from sugar phosphate to pyruvate. Summary of Glycolysis I. Glycolysis-cytoplasmGlucose----> 2 pyruvic acid 2NAD + 2H---->2NADH 2ATP---->2ADP + 2P 4ADP + 4P----> 4ATP NET 2 ATP for cell use After Glycoysis • If oxygen is present: aerobic respiration – Aerobic respiration= glycolysis+CAC+OP • If oxygen is absent: anerobic respiration – Anerobic respiration =glycolysis + fermentation Is Oxygen present? Fermentation • Two types of Fermentation: – 1. Alcohol fermentation- pyruvate is converted into ethanol. – 2. Lactic acid fermentation- pyruvate is reduced (gains electrons from NADH+). (NADH+ NAD+)Lactate formed as waste product. Cellular Respiration • Carbohydrates, fats, and proteins can all be broken down by C.R. • Glucose most common molecule broken down by aerobic respiration. • 6O2 + C6H12O6 --> 6H2O + 6CO2 + energy • Exergonic release of energy is used to phosphorylate ADP to ATP. • The goal of cellular respiration is to regenerate ATP that is used by cells as main energy source. (ADP + P ATP) Oxidation-Reduction Reactions • Cellular Respiration - YouTube • Cellular respiration is an example of an oxidation reduction reaction. (Redox for short) • In redox reactions electrons are transferred from one reactant to another. • When a reactant loses electrons it is called oxidation. This causes a loss of energy. • When a reactant gains electrons it is reduced. This causes a gain of energy Another way a cell uses energy is by moving hydrogen, and electrons around. Giving a molecule hydrogen, increases the energy content of that molecule . For example compare gasoline with carbon dioxide. Which has more energy? Now look at their molecular structure Oxidizing a molecule, decreases the energy content of that molecule and reducing a molecule increases the energy content of that molecule. Oxidized Reduce 1. Remove H 1. Add H 2. Remove e- 2. Add e- 3. Add oxygen 3.Remove oxygen When NAD+ gains 2 electrons and hydrogen it is called NADH and when NADP+ gains 2 electrons and hydrogen it is called NADPH. Look at NAD+ and NADH and see where the extra hydrogen is Compare FAD and FADH2 and determine what is the difference between these two hydrogen carriers. Following Glycolysis with Oxygen • Glycolysis takes place in cytosol. • If oxygen is present, the pyruvate goes into the mitochondria to complete the second stage of cellular respiration: Citric Acid Cycle aka Kreb’s Cycle Citric Acid Cycle • Citric Acid Cycle • Main purpose of Kreb’s is to make electron carriers for Citric Acid Cycle Step by Step • 1. Pyruvate (3C) loses CO2, becomes 2C, NAD is reduced to NADH +H+, Coenzyme A joins the molecule and is now called Acetyl-CoA (2). – Happens between outer and inner m. membrane • 2. Acetyl CoA joins a 4C molecule forming a 6C molecule and Coenzyme A is released. • 3. 6C molecule is oxidized, another NAD+ is reduced to NADH, CO2 is released, and 5C molecule results. • 4. 5C molecule oxidized again, another NAD+ reduced to NADH, CO2 released, 1ATP generated, and a 4C molecule results. • 5. 4C molecule is oxidized, FADH to FADH2, NAD+ TO NADH, and the 4C molecule is ready to rejoin the acetyl CoA and start the cycle again. • Citric Acid Cycle CoA Actual Kreb’s Cycle Summary of Krebs- Occurs in mitochondrion 2X’s Pyruvate---> 3 CO2 6 CO2 1 ADP ---> 1 ATP 2 ATP 4 NAD ---> 4 NADH2 8 NADH 1 FAD ---> 1 FADH2 2 FADH2 The hydrogen found on pyruvate will be used to reduce NAD and FAD. Only one ADP is phosphorylated at the substrate level or directly by enzymes. Glycolysis and Citric Acid Cycle are both substrate level phosphorylation Step 3 of Cellular Respiration utilizes the process of oxidative phosphorylation. Step 3:Oxidative Phosphorylation aka Chemiosmosis • Located in cristae of mitochondria is the electron transport chain. More folds=more ATP produced. • ETC will make more ATP using NADH & FADH2. • Electrons from NADH & FADH2 will move down the ETC and pump H+ across the cristae membrane. • NADH & FADH are oxidized, and ADP is phosphorylated. Oxidative Phosphorylation • Each NADH =6H+ • Each FADH2=4H+ • ~2H+=1ATP • Notice outside the the difference in (+) and (-) • ATP synthase uses the osmotic difference to allow H+ to go back into the matrix. • Oxygen is the final eacceptor. 8 NADH2 x 6 H = 48 H+ 2 FADH2(Krebs)x 4 H = 8 H+ 2 FADH2(glyc.) X 4 H = 8 H+ 64 H+ ATP Summary 64 H+ --> 32 ATP Electron Transport Chain • Electron transport chain powered by electrons from NADH and FADH. • As these electrons lose energy, that energy is used to pump H+ into intermembrane space. • At end of ETC, hydrogen bonds to oxygen to form water. No oxygen the process stops. • Cellular Respiration (Electron Transport Chain) • ATP Synthase Chemiosmosis • Hydrogen ions will flow back down concentration gradient through a transmembrane protein called ATP synthase. • The H ions provide a concentration gradient (fuel) that drives ATP synthesis. • ADPATP in this step Oxidative Phosphorylation • This term is used because ADP is phosphorylated into ATP, and oxygen is necessary to keep electrons flowing in the ETC. • Total ATP Yield for Cellular Respiration: 36-38 ATP. • 32-34 ATP come from oxidative phosphorylation. “Building” the proton concentration gradient Inner mitochondrial membrane Glycolysis Citric acid cycle ATP ATP Oxidative phosphorylation: electron transport and chemiosmosis ATP H+ H+ H+ H+ Intermembrane space Cyt c Protein complex of electron carriers Q IV III I ATP synthase II Inner mitochondrial membrane FADH2 NADH + H+ 2H+ + 1/2 O2 NAD+ ATP ADP + P i (carrying electrons from food) Mitochondrial matrix H2O FAD H+ Electron transport chain Electron transport and pumping of protons (H+), Which create an H+ gradient across the membrane Oxidative phosphorylation Chemiosmosis ATP synthesis powered by the flow of H+ back across the membrane ATP Synthetase Complex using kinetic movement of H+ (protons) ATP WEBSITE • • • • ATPl Oxidative Phosphorylation Animation You Tube- ox phos cellrespiration review song- Black Eyed Peas Data Set 4 Picture C A B D • The correct answer is B. This species is not struggling to exist. The environment is very favorable as it is making and storing more energy than it is consuming on metabolism, growth, repair, and reproduction. It has energy to spare. • • Answer A is incorrect because species B is consuming more energy than it can produce. It must be a harsh environment because it is consuming more energy trying to “stay alive”. At this pace, it will eventually die from an energy production deficit. • Answer C is incorrect because species D, while very much in the “high green” part of the curve, is only still at the • breakeven point on the y axis. Life is a struggle to exist here because any little disruption to the environment may put the species in a energy deficit situation where Cellular respiration is consuming more energy than being produced. • Answer D is incorrect for same reason as answer C. Cellular Respiration Lab (Lab #5) • Lab 5 Set Up • Make sure to time calibration times! • Practice drawing cell respiration on boards in down time. • Practice writing out steps in down time. • Begin answering questions.