Cellular Respiration: An Interactive Study Guide

Cellular Respiration Name:________________________________________ Things to do: Click on the following link and watch the animation a few times until you can answer number 1 on your handout. 1. Fill in the blanks by watching the animation. During glycolysis a 6C (6 carbon) molecule is to converted to pyruvate and 2 ATP energy molecules are released and 2 NADH are made which go to the electron transport chain. The 3C molecules leave glycolysis and are converted to a 2C molecule and CO2 is released (eventually into the air). The 2C molecules then enter the Krebs cycle and are combined with a 4 C molecule which is then broken back down to a 4 C molecule releasing CO2 into the air (eventually). 2 ATP molecules are also made that can power other reactions and the molecules NADH and FADH2 are made which deliver electrons (e-) to the electron transport chain. As electrons (e-) move down the electron transport chain ATP (important energy molecule) is made and the electrons are added to oxygen (O) and H2O is made. Click on the following link and navigate your way through the site by following the directions. You need to answer questions 2-7 on your handout. Click on the “Big Picture” section. Click the play arrowhead. 2. What are the overall products of cellular respiration and what function does it serve in organisms? CO2 (6), H2O (6), & Energy (ATP) Cellular respiration provides organisms with energy by generating ATP Return to Menu. Click on the “Glycolysis” section. Click the play arrowhead. 3. In this stage, glucose, a 6 carbon sugar is broken down into 2 pyruvate molecules, which are 3 carbon sugars. 4. What type of energy molecules are produced in this stage of cellular respiration? ATP and NADH 5. Describe what NADH is made of and its function. NADH is made of NAD+ and electrons (e-) and H+. The function is to carry the electrons to the ETC. The electrons have energy to be used in the ETC. Return to Menu. Click on the “ETC” section. Click the play arrowhead. 1 6. Where in the mitochondria is the electron transport chain located? inner membrane 7. Name the electron carriers used in Cellular Respiration. What is the function of electron carriers? NADH and FADH2 - they donate electrons to the ETC 8. What process is powered by electrons moving down the transport chain? Hint: involves creating a gradient. the movement of H+ across the membrane 9. What is the function of oxygen? To bind the electrons at the end of the ETC. The electrons have to be removed from the ETC for it to continue. 10. Where is the proton gradient formed (specific space)? How are protons represented? intermembrane space - between the inner and outer mitochondrial membrane 11. How is ATP made? FYI this protein complex is also referred to as ATP synthase. Chemiosmosis (best answer - most specific), oxidative phosphorylation (overall process) 12. What happens if there is not a proton gradient? No more ATP is made 13. What happens to the electron carriers when they leave the electron transport chain? They go back to glycolysis and Krebs cycle to pick up more electrons. Just to clarify. The entire process described for this section is oxidative phosphorylation. Ox phos is made of two components, the ETC (electron transport chain) and Chemiosmosis. Discuss / describe these two terms and which questions above are focused on each component. ETC is the movement of electrons from one protein to another. This movement of electrons provides the proteins energy to pump H+ from the mitochondrial matrix to the intermembrane space. (#7 - 9, 13) Chemiosmosis is the process of H+ moving down its concentration gradient, through ATP synthase and powering the formation of ATP. (#10 -12) 2 Click on the following links to learn more about the How the Krebs cycle works. Use this link to answer the following questions. 14. Pyruvate is made into Acetyl CoA before it can enter the Krebs cycle 15. List the products made from pyruvate conversion. Which is a waste product (not used in the Krebs cycle? CO2 (waste product) and Acetyl CoA 17. List the products (and total number of each) made from each acetyl CoA molecule after a round of the Krebs cycle. 2 CO2, 1 FADH2, 3 NADH, 1 ATP 18. Why is this a cycle? because the molecules are regenerated and used over and over 19. How many times does the Krebs cycle have to cycle for one molecule of glucose? twice (2 pyruvate 2 acetyl CoA 20. What is the location of the citric acid cycle in Eukaryotes? This is not specifically stated in the video, but you should know it. mitochondrial matriz 21. Critical thinking: What are the products of the Krebs cycle that are required for oxidative phosphorylation? (You may have to look at your answers in the ETC section above.) 2 FADH2, 6 NADH Additional information for these stages (some have more information than you need to know for this class, but you may find them helpful to explain these processes). “Krebs Cycle Overview animation” “Cellular Respiration (Electron Transport Chain)” “Mechanism of ATP synthase” “Acetyl CoA and Krebs Cycle” “Electron Transport Chain” 3 Click on the following links to learn more about the Fermentation. Use this link to answer the following questions. 22. Under what conditions does fermentation happen? when there is a lack of oxygen 23. What is the starting process for fermentation? glycolysis 24. What is the purpose of fermentation? to regenerate NAD+ so that glycolysis and a little ATP production can occur 25. What is the difference between alcoholic and acid fermentation? What is common? difference is what they produce: CO2 and ethanol for alcoholic fermentation lactic acid for the acid fermentation both start with glycolysis, both make NAD+ 4 Practice Review Questions: 1. Which of the following stages of respiration does not yield ATP? a. Glycolysis b. Pyruvate conversion c. Krebs Cycle d. Oxidative Phosphorylation 2. Where does glycolysis take place? a. Cell cytoplasm b. Mitochondrial matrix c. Inner mitochondrial membrane d. Outer mitochondrial membrane 3. Where does oxidative phosphorylation take place? a. Cell cytoplasm b. Mitochondrial matrix c. Inner mitochondrial membrane d. Outer mitochondrial membrane 4. Where is pyruvate converted to Acetyl CoA? a. Cell cytoplasm b. Mitochondrial matrix c. Inner mitochondrial membrane d. Outer mitochondrial membrane 5. Which stage of respiration generates most ATP? a. Glycolysis b. Pyruvate conversion c. Krebs Cycle d. Oxidative Phosphorylation 6. What happens to some of the hydrogen carried to the electron transport chain? a. It ends up as water b. It forms lactate c. It is recycled to Glycolysis d. It forms methane 7. What happens during the process of oxidative phosphorylation? a. A high concentration of electrons is built up in the intermembrane space b. A high concentration of protons is built up in the mitochondrial matrix c. A high concentration of protons is built up in the intermembrane space d. A low concentration of electrons is built up in the mitochondrial matrix 5 Short answer practice questions. 1. Where does cellular respiration occur in eukaryotes? (hint: it is an organelle) mitochondria 2. Draw out the structure of the Mitochondria. What is the main function of this organelle? The main function of the mitochondria is to take food and convert it to ATP 3. Label where each of the stages of cellular respiration occur in the cell using the diagram below. 4. Compare aerobic respiration and anaerobic respiration. What do these terms mean? Aerobic respiration, meaning requires oxygen, occurs with the presence of oxygen and produces a lot of ATP. Anaerobic respiration, meaning without oxygen, occurs in organisms that use something other than oxygen as the final electron acceptor. Aerobic respiration occurs in both prokaryotes and eukaryotes while anaerobic only takes place in prokaryotes. Fermentation, a type of anaerobic process takes place in both eukaryotes and prokaryotes. Fermentation is NOT the same as anaerobic respiration. 6 5. What is the purpose of fermentation? What are the two different types of fermentation and which type do humans use during anaerobic exercise? The purpose of fermentation is to regenerate NAD+ to keep glycolysis going. The two types of fermentation are lactic acid and alcohol. Humans use lactic acid during anaerobic exercise. 6. What is the main difference between substrate level phosphorylation and oxidative phosphorylation for ATP production? (hint: where is the ATP generated from in each?) Substrate phosphorylation directly phosphorylates ADP with a phosphate group whereas oxidative phosphorylation takes into account the electrons, H+ gradient, and ATP synthase. 7. Explain how the ATP synthase complex works to produce ATP in oxidative phosphorylation. As H+ ions move down the electrogradient through the ATP synthase enzyme, the bond between ADP and P is created making ATP. The H+ gradient is made by the ETC. ATP is synthesized by chemiosmosis. Together these two processes are called oxidative phosphorylation. Synthesis questions: 1. Explain how cellular respiration relates to life in humans. Describe how the reactants and products of the process are related to the substances an organism consumes and releases as waste. A good answer recognizes that the necessary reactants for cellular respiration are glucose (fuel/food), and oxygen, the same basic demands of humans. The main waste product is CO2, which is exchanged for O in the lungs. What we experience on a high level, of taking in food and air, converting that to energy, and then releasing waste products, is essentially the same as what happens on the cellular level. 2. Cellular respiration is a complex process, comprised of dozens of sequential steps. What is an advantage of such a complicated process, and what benefits could that provide an organism? The advantage of cellular respiration taking place over many steps is that it allows a cell to extract energy from macromolecules in a controlled, gradual manner. This can result in more efficiency for an organism because it does not experience spikes in available energy, and can sustain itself longer between input of energy/fuel sources (such as glucose). At the organismal level, this could mean that an organism can have a more controlled metabolism, and will not have to spend the majority of its time looking for food, or could sustain itself longer between feedings 3. Rotenone is a poison that blocks the transfer of electrons from Complex I of the electron transport chain to ubiquinone. What effect would this have on the process of cellular respiration? Which stage of 7 cellular respiration would be most impacted by this? Be sure to explain all of the biological mechanisms that will be affected, and how they will change. Because rotenone blocks electrons from completing their path down the ETC, the process most directly affected would be the establishment of a proton gradient across the inner membrane of the mitochondria. This will in turn result in an inability to power the ATP Synthase enzyme, and ATP production via oxidative phosphorylation will be prevented. This will result in cells no longer having the energy they need to carry out metabolic processes, and systems will begin to shut down. 8