Cell Respiration Chapter 2

Cell Respiration Energy Transfer Identify three different types of chemical energy ATP - an immediate energy source used by cells to fuel biological processes 1. …………………………………………………………………………………………………………………………………………………... Hydrogen / electron carriers (e.g. NADH) - an intermediate / transitional energy form 2. ………………………………………………………………………………………………………………………………………………….. Organic molecules - stored energy (e.g. carbohydrates and triglycerides) 3. …………………………………………………………………………………………………………………………………………………... Complete the following table Oxidation Reduction Electrons Loss Gain Hydrogen Loss Gain Oxygen Gain Loss Mitochondrion Label the different parts of a mitochondrion 1 Inner membrane (site of ETC) 1. ……………………………………………………………… 3 Outer membrane 2. ……………………………………………………………… 4 Matrix 3. ……………………………………………………………… Cristae (ruffling of inner membrane) 4. ……………………………………………………………… 2 5 Intermembrane space 5. ……………………………………………………………… Explain how electron tomography is used to produce images of active mitochondria Electron tomography involves repeated imaging of a mitochondria with a transmission electron microscope ………………………………………………………………………………………………………………………………………………….......... These cross-sections are taken at different angles and along distinct planes ………………………………………………………………………………………………………………………………………………….......... The images are then compiled by computer to generate 3D representations of the organelle ………………………………………………………………………………………………………………………………………………….......... ………………………………………………………………………………………………………………………………………………….......... ………………………………………………………………………………………………………………………………………………….......... Explain the relationship between the structure of the mitochondrion and its function Structure Function Inner membrane Highly folded (increases SA:Vol ratio so more oxidative phosphorylation occurs) Matrix Has appropriate enzymes and suitable pH for the Kreb cycle to occur Outer membrane Has appropriate carrier proteins for shuttling pyruvate into mitochondria Intermembrane space Small volume (maximises proton gradient with the accumulation of hydrogen ions) Aerobic Respiration State the four stages of aerobic respiration Glycolysis (occurs in the cytosol) 1. …………………………………………………………………………………………………………………………………………………... The link reaction (from cytosol to matrix) 2. ………………………………………………………………………………………………………………………………………………….. The Krebs cycle (matrix) 3. …………………………………………………………………………………………………………………………………………………... Electron transport chain (inner mitochondrial membrane) 4. …………………………………………………………………………………………………………………………………………………... Outline, with the aid of the following diagram, the process of glycolysis • Glucose is phosphorylated with 2 ATP (destabilising the molecule) ………………………………………………………………………………………………………………………………………………….......... • Molecule is then split in two (lysis) to form two 3C compounds ………………………………………………………………………………………………………………………………………………….......... • These compounds are oxidised (NADH is formed) ………………………………………………………………………………………………………………………………………………….......... • Four ATP molecules are produced (for a net gain of 2 ATP) ………………………………………………………………………………………………………………………………………………….......... • The final product is two molecules of pyruvate (3C) ………………………………………………………………………………………………………………………………………………….......... Outline the process of the link reaction • Pyruvate is transported from the cytosol into the mitochondrial matrix ………………………………………………………………………………………………………………………………………………….......... • Pyruvate is decarboxylated and oxidised (carbon dioxide and NADH is produced) ………………………………………………………………………………………………………………………………………………….......... • It is then converted to an acetyl compound and attached to coenzyme A to form acetyl CoA (2C) ………………………………………………………………………………………………………………………………………………….......... ………………………………………………………………………………………………………………………………………………….......... Outline, with the aid of the following diagram, the process of Krebs cycle • Acetyl CoA combines with a 4C compound (oxaloacetate) …………………………………………………………………………………… • The resulting 6C compound (citrate) is then broken back …………………………………………………………………………………… down into the original 4C compound (oxaloacetate) …………………………………………………………………………………… • This series of reactions involves decarboxylation (carbon …………………………………………………………………………………… dioxide is released) and oxidation (large amounts of …………………………………………………………………………………… hydrogen carriers are produced) …………………………………………………………………………………… • These reactions also produce 1 molecule of ATP per cycle …………………………………………………………………………………… …………………………………………………………………………………… Describe, with the aid of the following diagram, chemiosmosis at the electron transport chain Hydrogen carriers (e.g. NADH) donate high energy electrons to the electron transport chain ………………………………………………………………………………………………………………………………………………….......... As electrons move through the chain they lose energy, which is used to translocate protons to the ………………………………………………………………………………………………………………………………………………….......... intermembrane space - this creates an electrochemical gradient (or proton motive force) ………………………………………………………………………………………………………………………………………………….......... The proton gradient will cause the hydrogen ions to diffuse back into the matrix (chemiosmosis) ………………………………………………………………………………………………………………………………………………….......... ………………………………………………………………………………………………………………………………………………….......... Describe oxidative phosphorylation in terms of chemiosmosis Protons build up in the intermembrane space, creating a gradient ……………………………………………………………………………………………………… The protons can only return to the matrix via a transmembrane enzyme ……………………………………………………………………………………………………… called ATP synthase ……………………………………………………………………………………………………… The movement of protons through this enzyme triggers the formation ……………………………………………………………………………………………………… of ATP (from ADP and Pi) ……………………………………………………………………………………………………… Because the proton gradient was created by the oxidation of NADH, ……………………………………………………………………………………………………… this form of ATP production is called oxidative phosphorylation ……………………………………………………………………………………………………… Outline the role of oxygen in the electron transport chain De-energised electrons must be removed from the electron transport chain for it to continue to function ………………………………………………………………………………………………………………………………………………….......... (otherwise the chain would become blocked) ………………………………………………………………………………………………………………………………………………….......... Oxygen is the final electron acceptor - it takes the electrons (along with protons from the matrix) to ………………………………………………………………………………………………………………………………………………….......... form water (the removal of protons also helps to maintain the gradient needed for chemiosmosis) ………………………………………………………………………………………………………………………………………………….......... Complete the following table outlining the location of key events in aerobic respiration Decarboxylation Oxidation 2 NADH Glycolysis Link Reaction 2 x CO2 2 NADH Krebs Cycle 4 x CO2 6 NADH 2 FADH2 NET 2 ATP (substrate level) 2 ATP (substrate level) 32 ATP (oxidative phosphorylation) Electron Transport Chain Total ATP Formation 6 x CO2 36 ATP