7/19/2014 Metabolism Cellular Metabolism Metabolism Consists of all of the chemical reactions that take place in a cell PLAY Animation Breaking Down Glucose For Energy Biol 105 Lecture Packet 6 Read Chapter 3 (pages 56 62) Cellular Metabolism Aerobic cellular respiration requires oxygen, produces carbon dioxide Aerobic Cellular respiration Electrons transferred by Cytoplasm Blood vessel Glucose Anaerobic Fermentation does not require oxygen Electrons transferred by Plasma membrane Electrons transferred by and FADH 2 In aerobic cellular respiration cells take in sugar (glucose) and break it down to into carbon dioxide and water, this requires oxygen. Carrier protein Citric Acid Cycle Transition Reaction glucose pyruvate This process produces energy in the form of ATP Electron Transport Chain Oxygen Mitochondrion Extracellular fluid +2 ATP +2 ATP +32 ATP 36 ATP Figure 3.27 C6H12O6 + 6O2 6CO2 +6H2O + Energy Aerobic Cellular respiration There are four steps of aerobic cellular respiration: 1. 2. 3. 4. Transition Reaction (Krebs Cycle) Electron 1
7/19/2014 Cellular Respiration - Phase 1: Occurs in the cytoplasm Splits one glucose into two pyruvate molecules Generates a net gain of 2 ATP and 2 molecules Does not require oxygen Cellular Respiration - Starts with glucose Ends with 2 ATP, 2, 2 pyruvate and FADH2 are important carriers of electrons Song - Video (in cytoplasm) PLAY Cytoplasm During the first steps, two molecules of ATP are consumed in preparing glucose for splitting. Glucose 2 ATP Energyinvestment phase Come on sugar, for the breakdown! In Cytosol During the remaining steps, four molecules of ATP are produced. 2 ADP 4 ADP 4 ATP The two molecules of pyruvate then diffuse from the cytoplasm into the inner compartment of the mitochondrion, where they pass through a few preparatory steps (the transition reaction) before entering the citric acid cycle. 2 NAD+ Energyyielding phase 2 2 Pyruvate Two molecules of nicotine adenine dinucleotide (), a carrier of high-energy electrons, also are produced. Cellular Respiration Transition Reaction Figure 3.23 Transition Reaction Transition Reaction Transition Reaction (in mitochondrion) Phase 2: Transition reaction Start with: Pyruv ate (from glycolysis) Occurs within the mitochondria Coenzyme A combines with pyruvate and CO2 is removed from each pyruvate Forms 2 acetyl CoA molecules Produces 2 2 pyruvate (3 carbon molecules) 2 Coenzyme A One carbon (in the form of CO2) is removed from pyruvate. A molecule of is formed when gains two electrons and one proton. CO2 NAD+ End with: Coenzyme A 2 CO2 2 2 Acetyl CoA (2 carbon molecule) (electron passes to electron transport chain) CoA Acetyl CoA The two-carbon molecule, called an acetyl group, binds to coenzyme A (CoA), forming acetyl CoA, which enters the citric acid cycle. Figure 3.24 2
7/19/2014 Cellular Respiration Citric acid cycle (in mitochondrion) Phase 3: Citric acid cycle Occurs in the mitochondria Acetyl CoA enters the citric acid cycle Releases 2 ATP, 2 FADH2 and 6, 4 CO2 molecules Requires oxygen, but does not use oxygen Also called the Krebs Cycle Acetyl CoA, the two-carbon compound formed during the transition reaction, enters the citric acid cycle. The citric acid cycle also yields several molecules of FADH2 and, carriers of high-energy electrons that enter the electron transport chain. Start with 2 Acetyl CoA Acetyl CoA CoA CoA Oxaloacetate Citrate End with: CO2 leaves cycle 4 CO2 2 ATP 6 and 2 FADH2 Malate FADH 2 ATP FAD ADP + Pi -Ketoglutarate Succinate CO2 leaves cycle Krebs- Video PLAY KREBS! Cellular Respiration The Big Pay Off Electron Figure 3.25 The Big Pay Off Electron and FADH2 are important carriers of electrons Phase 4: Electron transport chain Electrons of FADH2 and are transferred from one protein to another, until they reach oxygen Releases energy that results in 32 ATP Requires oxygen The citric acid cycle yields One ATP from each acetyl CoA that enters the cycle, for a net gain of two ATP. They donate electrons to the electron transport chain At the end of the chain oxygen accepts the electrons. Electron Electron (inner membrane of mitochondrion) Electron produces ATP using the ATP synthase protein molecule The molecules of and FADH2 produced by earlier phases of cellular respiration pass their electrons to a series of protein molecules embedded in the inner membrane of the mitochondrion. High NAD+ The Electron produces 32 ATP As the electrons are transferred from one protein to the next, energy is released and used to make ATP. Potential energy FADH2 Membrane proteins FAD Ev entually, the electrons are passed to oxygen, w hich combines w ith tw o hydrogens to form w ater. Low 2 H+ + Energy released is used for synthesis of ATP H2O 1 2 O2 Figure 3.26 3
7/19/2014 How is ATP made using the ETC 1. In the mitochondria, the and FADH donate electrons to the electron transport chain (ETC) 2. Oxygen is the final electron acceptor from the ETC 3. The ETC uses the energy from the electrons to transport H + against the concentration gradient, transporting them from the lumen of the mitochondria to the intermembrane space. How is ATP made using the ETC 4. The ATPsynthase transports the H + back to the lumen of the mitochondria. 5. The H + falling through the ATPsynthase provides the energy for the ATPsynthase to catalyze the reaction of ADP + P ATP Electron (virtural cell) Intro to ETC One molecule of glucose is broken down and 36 ATP are generated. ATP Synthase Oxygen is used by the electron transport chain it accepts electrons from the ETC Carbon dioxide is produced by the Transition Reaction and the Citric acid cycle Table 3.5 : Starts the process by taking in glucose. Produces 2 ATP The Transition Reaction produces CO 2 and The Citric acid cycle: Produces 2 ATP but also produces lots of and FADH 2. Produces CO 2. Electron transport chain Takes electrons from and FADH 2 and uses them to produce ATP using the ATP synthase molecule. Requires oxygen. Oxygen is the final electron acceptor on the electron transport chain One glucose can produce a total of 36 ATP Complex Carbohydrates must first be broken down into glucose before entering glycolysis Fats and proteins enter the process at different steps 4
7/19/2014 Oxygen Anaerobic Fermentation Anaerobic Fermentation Cellular respiration requires oxygen this is aerobic cellular respiration Sometimes organisms, including humans, need to produce energy without using oxygen Breakdown of glucose without oxygen Takes place entirely in the cytoplasm Anaerobic Fermentation: Anaerobic pathway to produce ATP from glycolysis without the Krebs and ETC When you need energy quick, or if there is not enough O 2 then the cell will use only glycolysis It is very inefficient - results in only two ATP Fermentation in Animals What is the starting molecule of glycolysis? When cells need energy quick they will use this pathway for a short time 2 pyruvic acid + 2 2 lactate and 2 End result = lactate and 2 ATP produced (from glycolysis) and is regenerated 1. Acetyl CoA 2. Protein 3. Glucose 4. Pyruvate (pyruvic acid) 25% 25% 25% 25% Acetyl CoA Protein Glucose Pyruvate (pyruvic acid) Which stage produces CO 2 Which stage uses O 2 Which stage produces the most s 1. 2. Electron 3. Transition 4. Citric acid Cycle 5. Both 3 and 4 20% 20% 20% 20% 20% 1. 2. Krebs Cycle 3. Electron 33% 33% 33% 1. 2. Krebs Cycle 3. Electron 33% 33% 33% Transition Citric acid Cycle Both 3 and 4 Krebs Cycle Krebs Cycle 5
7/19/2014 Which stage produces the most ATP 1. 2. Krebs Cycle 3. Electron 33% 33% 33% Krebs Cycle Important Concepts What is Cellular respiration and Anaerobic Fermentation and what are the differences between them. What are the four steps of aerobic cellular respiration, what happens in each step, what are the starting molecules, what comes out of each step, where in the cell does each step occur, how many ATP and /FADH 2 are produced in each step. Important Concepts Describe in detail how is ATP made using the electron transport chain What is the role of ATPsynthase, H +, O 2, and FADH 2 and the electron transport chain in ATP production? Know the overall picture of cellular respiration (summary slides) Important Concepts What is the role of oxygen in cellular respiration, what steps produce carbon dioxide What is anaerobic fermentation, what steps are involved in fermentation, what end products are produced in humans, is oxygen required? when is it used. Definitions Aerobic cellular respiration, anaerobic fermentation, ATP synthase, metabolism 6