1 3.7 Cell Respiration 1. Define cell respiration. Cell respiration is the controlled release of energy from organic molecules in cells to form ATP. 2. State the equation for the process of cell respiration. C 6H 12O 6 + 6O 2 6CO H 2O + Energy 3. Distinguish between aerobic and anaerobic in terms of cell respiration. Outline the general process of both. Aerobic pathways require oxygen, and use glycolysis, the link reaction, Krebs cycle, and oxidative phosphorylation to produces a large amount of ATP (36). Anaerobic pathways do not require oxygen, produce lactic acid/lactate through lactic acid fermentation, produces ethanol through alcoholic fermentation, occurs only in the cytoplasm of the cell, and produces a small amount of ATP (2) Process Aerobic respiration breaks glucose down into pyruvate during glycolysis, pyruvate is converted into the acetyl coa in the link reaction, which then joins with oxaloacetate to form citrate in the krebs cycle. Here it is oxidized and decarboxylated forming NADH and FADH 2, as well as ATP. NADH and FADH 2 transfer electrons to the Electron Transport Chain, where chemiosmosis and oxidative phosphorylation occurs. Anaerobic respiration occurs in the cytoplasm, where glucose is broken down into pyruvate. In order to continue to produce energy, NADH needs to be recycle into NAD +, where pyruvate is reduced and forms lactate in lactic acid fermentation, or it is decarboxlyated and reduced to form ethanol in alcoholic fermentation. (haven t learned this yet) 4. Complete the table below summarizing the events of aerobic cell respiration. Reaction Location Purpose ATP yield Glycolysis Cytoplasm Split glucose into pyruvate and produce NADH and ATP 2 Link Reaction Matrix of the mitochondrion Convert pyruvate (3C) to acetyl CoA (2C) 0 Krebs Cycle Matrix of mitochondrion Form NADH, FADH 2, and ATP 2 Electron Transport Chain/Chemiosmosis Oxidative phosphorylation Inner mitochondrial membrane Inner mitochondrial Membrane Generate concentration gradient using movement of electrons to power ATP synthase Movement of ions through ATP synthase to form ATP, using energy from movement of electrons
2 8.1/C3 Cell Respiration (AHL/Option content) 5. Many reactions in living things can be classified as either oxidation or reduction reactions. These are particularly important in cell respiration and photosynthesis. Complete the table below to compare oxidation and reduction reactions. OXIDATION REDUCTION Electrons are lost Gained Oxygen is Gained Lost Hydrogen is Lost Gained 6. Define phosphorylation. Addition of a phosphate group to a molecule. Substrate level phosphorylation occurs when an enzyme transfers an electron directly from a substrate to a molecule of ADP. Oxidative phosphorylation occurs using the movement of electrons to generate energy used to add a phosphate to a molecule of ADP. Makes molecules less stable 7. In the space below, draw a diagram to show the process of glycolysis. Process of breaking glucose down into pyruvate, using two molecules of ATP to start the process. This forms 2 pyruvate molecules, as well as 2 molecules of NADH, and a net gain of 2 ATP molecules. 8. Explain the link reaction, including oxidative decarboxylation and conversion of pyruvate to acetyl CoA and CO 2. In the link reaction, both pyruvate molecules are decarboxylated (lose a carbon which forms CO 2), oxidized (lose electrons), and combined with a molecule of coenzyme A to form 2 NADH and 2 acetyl CoA.
3 9. Complete the table below with the functions of the structures of the mitochondrion. How is each structure adapted to help maximize efficiency of respiration? Structure: Outer membrane Inner membrane (including christae) Matrix Inter-membrane space Function: Separates internal and external components of mitochondrion and controls entry/exit of materials Location of Electron Transport Chain and ATP synthase, pumps electrons and generates gradient to produce ATP and water. Contains enzymes for link reaction and Krebs cycle to produce acetyl CoA, NADH, and FADH 2, and ATP Area where hydrogen ions accumulate to generate concentration gradient and proton motive force. 10. List two electron carriers that are used in cell respiration. NADH FADH Outline the process of the Krebs Cycle. Acetyl CoA will combine with a molecule of oxaloacetate to form Citrate. Citrate will be decarboxylated (loses carbon, forms CO 2) and go through a series of redox reactions (transfer of electrons) to regenerate oxaloacetate. Decarboxylation will produce 2 CO 2 and the redox reactions will produce 3 NADH and 1 FADH 2 by transferring electrons from citrate to the electron carriers. ATP will also be produced by substrate-level phosphorylation. For each molecule of glucose that is broken down, the Krebs cycle will turn twice, producing 6 molecules of NADH, 2 molecules of FADH 2, 4 molecules of CO 2, and 2 molecules of ATP.
4 12. Annotate the diagram below with the stages of the electron transport chain and oxidative phosphorylation. Include generation of a concentration gradient in the inter-membrane space, movement of electrons, oxidative phosphorylation by ATP synthase, use of O 2 as the terminal electron acceptor e - NADH NAD + e - FADH2 FAD + NADH and FADH 2 will donate electrons to electron acceptors in the ETC. The electrons will pass down the chain to the final electron acceptor, oxygen, which will then combine with two hydrogens to form water. As the electrons move down the ETC, the proteins will pump hydrogen ions from the matrix to the intermembrane space, generating a concentration gradient, which generates a proton motive force (potential energy). The hydrogen ions will move through the ATP synthase, which will uses the energy from the ions to add a phosphate molecule to ADP, forming ATP. O H2O + ADP + P ATP 13. In the space below, define the terms electron transport chain, chemiosmosis, and oxidative phosphorylation Electron transport chain - series of molecules (mainly proteins) that accept and donate electrons as they pass from NADH/FADH 2 to the final electron acceptor oxygen (which then combines with and leaves as water) releasing small amounts of energy along the way. It also pumps ions from the matrix to the intermembrane space, creating a hydrogen ion concentration gradient. Chemiosmosis - is the movement of hydrogen ions (by the electron transport chain) to create a hydrogen ion concentration gradient. This gradient creates a proton-motive force, which stores energy that can be used to power ATP Synthase, an enzyme that combines ADP and a phosphate to form ATP. Oxidative Phosphorylation - uses energy from the movement of electrons/hydrogen ions to add a phosphate to a molecule of ADP, forming ATP. This produces roughly molecules of ATP per 1 glucose.