How Cells Release Chemical Energy Chapter 7

Mitochondria Structure Organelle of cell respiration Mitochondria Structure Cristae or

Energy flow in the ecosystem Relationship of Photosynthesis and Cellular Respiration Basis of Energy flow in the ecosystem p.107d

Who can Respire? p.108

Overall Concept of Cellular Respiration p.106a

Fig. 7-2, p.108

Energy-Requiring Steps of Glycolysis fructose1,6-bisphosphate 2 ATP invested Energy-Requiring Steps of Glycolysis glucose ADP P ATP glucose-6-phosphate P fructose-6-phosphate ATP fructose1,6-bisphosphate P ADP PGAL P Stepped Art Fig. 7-4, p.111

ENERGY-RELEASING STEPS OF GLYCOLYSIS substrate-level phosphorylation PGAL PGAL NAD+ NADH NAD+ NADH Pi Pi P P P P 1,3-bisphosphoglycerate 1,3-bisphosphoglycerate substrate-level phosphorylation ADP ATP ADP ATP 2 ATP invested P P 3-phosphoglycerate 3-phosphoglycerate P P 2-phosphoglycerate 2-phosphoglycerate H2O H2O P P PEP PEP ATP substrate-level phosphorylation ADP ADP ATP 2 ATP invested pyruvate pyruvate Fig. 7-4b, p.111 to second set of reactions

Glycolysis review In cytoplasm Uses glucose, 2 ATP, 2 NAD Makes 2 pyruvates, 4ATP, 2NADH Net gain of ATP=2 Why 10 steps?

Acetyl-CoA Formation pyruvate coenzyme A NAD+ (CO2) NADH CoA Krebs Cycle CoA oxaloacetate citrate NAD+ NADH NADH NAD+ FADH2 NAD+ FAD NADH ADP + phosphate group ATP Fig. 7-7a, p.113

Krebs Cycle Begins after the Intermediate step Pyruvate Acetyl CoA + CO2 + NADH Acetyl CoA enters mitochondria matrix and reacts with oxaloacetate Citrate (aka citric acid cycle) A series of reactions will yield oxaloacetate again (aka cycle) Each pyruvate makes 3 NADH, 1FADH2, 1ATP, 2 CO2 How many per glucose?

Fig. 7-8b, p.114

Fig. 7-8c, p.114

Electron Transport Chain Mitochondrial membrane or cristae Enzymes (Cytochromes) and ATP synthase on membrane to shuttle electrons and protons NADH, FADH2 gives up the H H+ + e- Electrons are passed through the membrane proteins and the energy released is used to transport the H to the outer membrane The gradient established is the force needed to allow the H to move back into the inner membrane through ATP Synthase The 4H + 4e + O2 H2O What is the purpose of the oxygen?

How many ATP’s was that? Each NADH can make 3ATP and FADH2 2ATP ____ATP From glycolysis ____NADH from Glycolysis x ___ = ____ATP From Krebs Cycle ____NADH from Krebs cycle x ___ = _____FADH2 from Krebs x _____ = Total ATP ______

2 ATP net 2 pyruvate energy output energy input ATP NADH 2 NAD+ 2 ADP 2 pyruvate 4 energy output energy input GLYCOLYSIS ATP C6H12O6 NADH 2 NAD+ electrons, hydrogen from NADH 2 ethanol ETHANOL FORMATION 2 acetaldehyde 2 CO2 2 H2O Stepped Art Fig. 7-10, p.116

Fig. 7-10b, p.116

electrons, hydrogen from NADH LACTATE FORMATION ATP C6H12O6 NADH 2 NAD+ 2 2 ADP 2 pyruvate 4 energy output energy input GLYCOLYSIS 2 ATP net 2 lactate electrons, hydrogen from NADH LACTATE FORMATION Stepped Art Fig. 7-11, p.117

Fig. 7-12a, p.117

What is the purpose of anaerobic respiration? To continue making ATP even in the absence of oxygen Can happen in glycolysis but soon .. NADH are used up Cannot be regenerated in ETC So has to be regenerated in the fermentation phase of cell respiration Side effects – formation of ethanol, CO2 or lactate

complex carbohydrates FOOD fats glycogen complex carbohydrates proteins fatty acids glycerol simple sugars (e.g., glucose) amino acids NH3 carbon backbones glucose-6-phosphate urea PGAL 2 ATP glycolysis 4 ATP (2 ATP net) NADH pyruvate Acetyl-CoA NADH CO2 NADH, FADH2 Krebs Cycle 2 ATP CO2 e– ATP ATP ATP many ATP H+ fats e– + oxygen Fig. 7-13b, p.119

Uses of Cell Respiration? ATP for cell work CO2 for photosynthesis Carbon skeletons for metabolism of sugars, lipids, proteins, nucleic acids, etc.