How Cells Release Chemical Energy Chapter 7

p.106a Overall Concept of Cellular Respiration

Mitochondria Structure Cristae or

p.107d ENERGY FLOW IN THE ECOSYSTEM

p.108

Fig. 7-2, p.108

P P Stepped Art P ATP P PP Fig. 7-4, p.111

ATP PGAL ATP NADH ATP 2 ATP invested ENERGY-RELEASING STEPS OF GLYCOLYSIS 2 ATP invested NAD + PiPi PiPi 3- phosphoglycerate 2- phosphoglycerate PEP ADP 1,3- bisphosphoglycerate PPPP PP PP PP pyruvate to second set of reactions substrate-level phosphorylation H2OH2O H2OH2O ADP Fig. 7-4b, p.111

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 acetyl-CoA (CO 2 ) pyruvate coenzyme A NAD + NADH CoA Krebs Cycle CoA NADH FADH 2 NADH ATP ADP + phosphate group NAD + FAD oxaloacetate citrate Fig. 7-7a, p.113

KREB’S 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, FADH 2 gives up the HH + + 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 + O 2 H2O What is the purpose of the oxygen?

HOW MANY ATP’S WAS THAT? Each NADH can make 3ATP and FADH 2 2ATP ____ATP From glycolysis ____NADH from Glycolysis x ___ = ____ATP From Kreb’s Cycle ____NADH from Kreb’s cycle x ___ = _____FADH 2 from KREb’s x _____ = Total ATP______

ETHANOL FORMATION 2 acetaldehyde 2 CO 2 2 H 2 O Stepped Art 2 ATP net 2 2 ADP 2 pyruvate 2 4 energy output energy input GLYCOLYSIS ATP C 6 H 12 O 6 NADH 2 NAD + electrons, hydrogen from NADH 2 ethanol Fig. 7-10, p.116

Fig. 7-10b, p.116

Stepped Art ATP C 6 H 12 O 6 NADH 2 NAD ADP 2 pyruvate 2 4 energy output energy input GLYCOLYSIS 2 ATP net 2 lactate electrons, hydrogen from NADH LACTATE FORMATION 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 regenerted in ETC So has to be regenerated in the fermentation phase of cell respiration Side effects – formation of ethanol, CO 2 or lactate

FOOD fatsglycogen complex carbohydrates proteins simple sugars (e.g., glucose) amino acids glucose-6- phosphate carbon backbones NH 3 urea ATP (2 ATP net) PGAL glycolysis ATP 2 glycerol fatty acids NADHpyruvate Acetyl-CoA NADHCO 2 Krebs Cycle NADH, FADH 2 CO 2 ATP many ATP fats H+H+ e – + oxygen e–e– 4 ATP 2 Fig. 7-13b, p.119

USES OF CELL RESPIRATION? ATP for cell work CO 2 for photosynthesis Carbon skeletons for metabolism of sugars, lipids, proteins, nucleic acids, etc