1. Fig. 7-2a, p.108

2. Fig. 7-2b, p.108 a All carbohydrate breakdown pathways start in the cytoplasm, with glycolysis. b Fermentation pathways are completed in the semifluid matrix of the cytoplasm. c In eukaryotes, aerobic respiration is completed inside mitochondria.

3. Cytoplasm GLYCOLYSIS Krebs Cycle ATP 6 CO 2 4 ATP (2net) 32 ATP 2 NADH 8 NADH, 2 FADH 2 2 pyruvate oxygen 2 ATP glucose ATP Fig. 7-3, p.109 ATP 2 ATP Electron Transfer Phosphorylation Mitochondrion a The first stage, glycolysis, occurs in the cell’s cytoplasm. Enzymes convert a glucose molecule to 2 pyruvate for a net yield of 2 ATP. During the reactions, 2 NAD+ pick up electrons and hydrogen atoms, so 2 NADH form. b The second stage, the Krebs cycle and a few steps before it, occurs inside mitochondria. The 2 pyruvates are broken down to CO2, which leaves the cell. During the reactions, 8 NAD+ and 2 FAD pick up electrons and hydrogen atoms, so 8 NADH and 2 FADH2 form. 2 ATP also form. c The third and final stage, electron transfer phosphorylation, occurs inside mitochondria. 10 NADH and 2 FADH2 donate electrons and hydrogen ions at electron transfer chains. Electron flow through the chains sets up H+ gradients that drive ATP formation. Oxygen

4. 2 NADH2 pyruvate 2 ADP (net) Fig. 7-4b, p.110 glucose to second stage of aerobic respiration or another pathway to third stage of aerobic respiration or another pathway Glycolysis

5. Fig. 7-5, p.112 outer mitochondrial compartment (in between the two membranes) inner mitochondrial compartment inner membrane outer membrane (next to cytoplasm) Krebs Cycle 2 acetyl–CoA Breakdown of 2 pyruvate to 6CO2 yields 2 ATP. Also, 10 coenzymes are reduced (8 NADH, 2 FADH2). The coenzymes carry hydrogen ions and electrons to sites of the third stage of aerobic respiration. INNER COMPARTMENT OUTER COMPARTMENT 2 pyruvate (glycolysis) glucose b The second stage starts after membrane proteins transport pyruvate from the cytoplasm, across both mitochondrial membranes, to the inner compartment. Six carbon atoms enter these reactions (in two pyruvate), and six leave (in six CO2). Many coenzymes form. a An inner membrane divides a mitochondrion’s interior into two compartments. The second and third stages of aerobic respiration take place at this membrane. FADH 2 NADH ATP CO2

6. Fig. 7-6, p.113

7. Krebs Cycle Fig. 7-6b, p.113 Glycolysis glucose you are here Electron Transfer Phosphorylation

8. Fig. 7-7, p.114

9. Fig. 7-7a, p.114 Krebs Cycle Glycolysis glucose you are here Electron Transfer Phosphorylation

10. Fig. 7-8, p.115 glucose Glycolysis 2 pyruvate Krebs Cycle Electron Transfer Phosphorylation (2 net) 2 NADH ATP 2 FADH 2 6 NADH 2 acetyl-CoA 32 ADP + P i H+H+ ATP 2 NADH ATP H+H+ H+H+ H+H+ H+H+ 2 NAD + 2 CO 2 4 CO 2 2 oxygen INNER MITOCHONDRIAL COMPARTMENT OUTER MITOCHONDRIAL COMPARTMENT CYTOPLASM water 2

11. Fig. 7-9, p.116

12. Fig. 7-10a, p.117

13. Fig. 7-11, p.117

14. Fig. 7-12a, p.119 FOOD fats COMPLEX CARBOHYDRATES PROTEINS glucose, other simple sugars amino acids Glycolysis glycerol fatty acids pyruvate acetyl-coA NADH Krebs Cycle NADH, FADH 2 PGAL acetyl-coA oxaloacetate or another intermediate of the Krebs Electron Transfer Phosphorylation

15. Fig. 7-13, p.120 sunlight energy in Driven by energy input from the sun, electrons and hydrogen are used to form ATP. ATP energy drives the synthesis of glucose from hydrogen, electrons (delivered by coenzymes), and carbon dioxide’s atoms. Photosynthesis energy out (heat) oxygen carbon dioxide, water glucose (stored chemical energy) Aerobic Respiration Energy input from two ATP initiates three stages of reactions. Many ATP form during thecomplete breakdown of glucose to carbon dioxide and water. chemical energy in many ATP available to drive nearly all cellular tasks energy out (heat)

16. p.122 Krebs Cycle Glycolysis 1 glucose Electron Transfer Phosphorylation pyruvate NADH CO 2 ATP (net) FADH 2 ATP