Ch. 6 Cellular Respiration Name Period California State Standards covered by this chapter: Cell Biology 1. The fundamental life processes of plants and animals depend on a variety of chemical reactions that occur in specialized areas of the organism's cells. As a basis for understanding this concept: f. Students know usable energy is captured from sunlight by chloroplasts and is stored through the synthesis of sugar from carbon dioxide. g. Students know the role of the mitochondria in making stored chemical-bond energy available to cells by completing the breakdown of glucose to carbon dioxide. i.* Students know how chemiosmotic gradients in the mitochondria and chloroplast store energy for ATP production. Ecology 6. Stability in an ecosystem is a balance between competing effects. As a basis for understanding this concept: d. Students know how water, carbon, and nitrogen cycle between abiotic resources and organic matter in the ecosystem and how oxygen cycles through photosynthesis and respiration. Read the appropriate section in the textbook and lecture notes before answering the following questions. You must put all answers and definitions into your own words for full credit. Energy Flow and Chemical Cycling in the Biosphere 1. photosynthesis: 2. autotrophs: 3. heterotrophs: 4. producers: 5. consumers: 6. Explain how chemical cycling occurs between photosynthesis and cellular respiration. (i.e. summarize the section on pp. 90-91. Cellular Respiration: Aerobic Harvest of Food Energy 7. Explain the difference between breathing and cellular respiration. 8. aerobic respiration: 9. The movement of electrons from one molecule to another is an reaction.
10. oxidation: 11. reduction: 12. Write the balanced chemical equation for cellular respiration. 13. What do you notice about the chemical reactions for cellular respiration and photosynthesis? The Metabolic Pathway of Cellular Respiration Three main stages of cellular respiration are glycolysis, the Krebs cycle, and the electron transport chain and chemiosmosis. Use the diagrams included in the back of this packet, the diagrams on pp.95-97, and the lecture notes to complete the following sentences. Glycolysis 14. Glycolysis occurs in the. It can take place oxygen. 15. Glycolysis can be divided into the energy stage and the energy stage. 16. For energy to be released from glucose, the cell must first invest some energy to get glycolysis started. This is accomplished through the phosphorylation of glucose by two molecules of. 17. As a result, the six-carbon sugar (glucose) is broken down to form two three-carbon molecules of glyceraldehyde 3-phosphate or. 18. During the energy yielding process, each G3P is, ( two hydrogens and their electrons) and a coenzyme NAD + is, ( the two and one of the hydrogens) forming NADH + H +. 19. ATP is produced as the attached to the two molecules of G3P are to two ADPs and the G3Ps are converted into 2 molecules of. 20. The two molecules of 3-PGA are chemically rearranged and more ATP is produced. Two are phosphorylated to produce ATP. Glycolysis has now produced two molecules of.
21. For each glucose molecule processed, what are the net molecular products of glycolysis? Pyruvate Oxidation 22. Before pyruvic acid (pyruvate) can enter the Krebs cycle, it must be oxidized to form. This is called pyruvate oxidation. The two pyruvic acid molecules are by two molecules of NAD + to produce two. 23. Two carbon dioxide molecules are, one from each pyruvic acid molecule. With the addition of two coenzyme A molecules (one for each pyruvic acid), two molecules of are produced. Citric Acid Cycle (Krebs Cycle) 24. The Krebs cycle is the biochemical pathway of respiration. Because (adjective) acid is involved, it is also called the citric acid cycle. The Krebs cycle takes (adjective) place in the mitochondrial. 25. It begins when one of the two-carbon acetyl-coa with a four-carbon compound, oxaloacetic acid (oxaloacetate), to form acid. (adjective) 26. A carbon dioxide molecule is released from the citric acid and NAD + is to form. This produces alpha-ketogluterate. 27. Another carbon dioxide molecule is released and another NAD + is to form. This produces succinate. 28. An ADP molecule is then to form a molecule of ATP. 29. Another electron carrier,, is reduced to FADH 2. This produces malate. 30. Malate is then by NAD + to produce NADH+ H + and regenerate. 31. Since glycolysis of glucose produces two molecules of pyruvate, the Krebs cycle takes another turn. This produces another ATP, NADH + H +, and FADH 2.
The Electron Transport Chain and Chemiosmosis 32. Glycolysis, the conversion of pyruvic acid, and pyruvate oxidation and the Krebs cycle complete the breakdown of glucose. Up to this point molecules of ATP have been produced. There has also been produced NADH + + H + and FADH 2. 33. NADH + H + and FADH 2 + H + are oxidized in a series of reactions involving imbedded in the inner mitochondrial membrane, each of greater electronegativity. This is called the electron chain. At the end of the chain is that acts as the final electron. 34. Water is by this process (figure 6.12). As the electrons are handed down the chain the released is used to pump through the membrane against the concentration gradient into the intermembrane space. 35. These hydrogen ions in turn, diffuse back into the mitochondrial matrix through another membranebound protein (enzyme), synthase, and are used to convert ADP into ATP. This process is called. 36. Each NADH + H + yields ATPs. Because FADH 2 enters the transport chain at a lower energy level, each FADH 2 only produces ATPs. 37. 2 mechanisms that generate ATP are chemiosmosis and substrate-level phosphorylation. Describe them. a. Chemiosmosis: b. Substrate-level phosphorylation: 38. Each molecule of glucose results in the following energy yield: a. 10 NADH + H + = ATP b. 2 FADH 2 = ATP
39. produces 4 ATP but 2 are used in the process so that the total from glycolysis is. The Krebs cycle yields more and the with chemiosmosis yields an additional ATP. The total ATP from one molecule of glucose is. 40. Why is NAD + called a hydrogen acceptor? 41. Which of the biochemical pathways involved in aerobic respiration produces the most ATP? Explain. Fermentation: Anaerobic Harvest of Food Energy 42. anaerobic respiration: 43. fermentation: 44. Describe the process of alcoholic fermentation. Do not simply copy the equation. 45. List 2 organisms that use alcoholic fermentation. 46. Describe the process of lactic acid fermentation. Do not simply copy the equation. 47. Explain how muscles cells get their energy during strenuous exercise. Start your explanation when exercise first begins.
QUESTIONS YOU SHOULD BE ABLE TO ANSWER. IT IS RECOMMENDED THAT YOU TRY TO ANSWER THESE. 1. Where, in eukaryotic cells, does glycolysis occur? 2. For each molecule of glucose, what are the net products of glycolysis? 3. What mediates each of the steps involved in glycolysis? 4. Explain what substrate-level phosphorylation is? 5. Explain, in words, the glycolysis pathway. 6. Explain, in words, how pyruvate is prepared for the Krebs cycle? 7. What is the function of NADH and FADH 2 molecules? 8. Where, in eukaryotic cells, would one expect to find enzymes necessary for the Krebs cycle? 9. What happens to NAD + during glycolysis and the Krebs cycle? 10. What is the total number of NADH molecules generated during the complete breakdown of 1 glucose molecule? Explain where they were produced. 11. Using your knowledge about cellular respiration, identify the number of molecules produced by each biochemical pathway during the breakdown of 2 or 3 or molecule(s) of glucose. Process Product ATP NADH FADH 2 Glycolysis Pyruvate Oxidation Krebs Cycle Electron Transport Chain & Chemiosmosis Total for Aerobic Respiration 12. Where does the carbon dioxide that we exhale come from? Explain. 13. Explain the function of the electron transport chain. Where does this occur? 14. At the end of the electron transport chain, when electrons are finally passed to oxygen, what waste product of cellular respiration is produced? 15. What is the potential energy source that directly drives ATP production by ATP synthase? 16. Of the three main stages of cellular respiration, which one uses oxygen directly to extract chemical energy from organic compounds? Explain. 17. What effect would an absence of oxygen have on chemiosmosis in the mitochondrion? 18. Explain the difference between cellular respiration and fermentation. 19. Explain the difference between alcoholic fermentation and lactic acid fermentation. 20. What is the biggest disadvantage of making ATP by means of fermentation? What is the biggest advantage of making ATP this way? 21. Explain in terms of cellular respiration why we need oxygen and why we exhale carbon dioxide.