Glycolysis & Cellular Respiration Interconnection of photosynthesis & cellular respiration ATP from Breakdown of Glucose to Carbon Dioxide & Water Summary Reaction Copyright © 2005 Pearson Prentice Hall, Inc.

Glycolysis & Cellular Respiration Occurs in Four Steps (F8.1 p. 133) Glycolysis in Cytoplasm Cellular Respiration in Mitochondrion Transport into Mitochondrion Krebs Cycle Electron Transport Chain Copyright © 2005 Pearson Prentice Hall, Inc.

mitochondrion inner membrane intermembrane compartment outer membrane matrix glucose cristae Figure :8-4 top Title: Cellular respiration top Caption: Cellular respiration occurs in mitochondria, whose structure accommodates the compartmentalized reactions that occur there. Note that the glycolysis that precedes cellular respiration occurs outside the mitochondrion in the cytoplasmic fluid. Glycolysis 2 pyruvate coenzyme A (intermembrane compartment) Copyright © 2005 Pearson Prentice Hall, Inc.

Glycolysis Fermentation Cellular respiration Krebs cycle Electron glucose (cytoplasm) Glycolysis ATP 2 C lactate or 2 C 2 pyruvate ethanol CO2 2 C + Fermentation 2 CO2 C Cellular respiration C 2 acetyl CoA 4 CO2 C Figure :8-1 Title: A summary of glucose metabolism Caption: Refer to this diagram as we progress through the reactions of glycolysis (in the fluid portion of the cytoplasm) and cellular respiration (in the mitochondria). The breakdown of glucose occurs in stages, with energy captured in ATP along the way. Most ATP is produced in the mitochondria. Krebs cycle 2 ATP electron carriers Electron transport chain 32 or 34 ATP intermembrane compartment H2O (mitochondrion) O2

Glycolysis & Cellular Respiration Glycolysis (F8.2 p. 133 & FE8.1 p. 134) Summary Reaction: Glucose => CO2 + NADH + ATP Copyright © 2005 Pearson Prentice Hall, Inc.

glucose A glucose molecule is energized by the addition of a high-energy phosphate from ATP. 1 glucose-6-phosphate 2 The molecule is slightly rearranged, forming fructose. fructose-6-phosphate 3 A second phosphate is added from another ATP. fructose-1,6-bisphosphate The resulting molecule, fructose-1,6-bisphosphate, is split into two three-carbon molecules, one DHAP (dihydroxacetone phosphate) and one G3P. Each has one phosphate attached 4 DHAP rearranges into G3P. From now on, there are two molecules of G3P going through the identical reactions. 5 DHAP G3P 2 glyceraldehyde 3-phosphate Each G3P undergoes two almost-simultaneous reactions. Two electrons and a hydrogen ion are donated to NAD+ to make the energized carrier NADH, and an inorganic phosphate (P) is attached to the carbon skeleton with a high-energy bond. The resulting molecules of 1,3-bisphosphoglycerate have two high-energy phosphates. 6 2 P 2 Figure: E8-1 Title: Glycolysis 2 2 1,3-bisphosphoglycerate One phosphate from each bisphosphoglycerate is transferred to ADP to form ATP, for a net of two ATPs. This transfer compensates for the initial two ATPs used in glucose activation. 7 2 2 2 phosphoglycerate 2 phosphoenolpyruvate After another rearrangement, the second phosphate from each phosphoenolpyruvate is transferred to ADP to form ATP, leaving pyruvate as the final product of glycolysis. There is a net profit of two ATPs from each glucose molecule. 8 2 2 2 pyruvate

Glycolysis & Cellular Respiration Glucose to Pyruvate Chemical Energy Released NADH & ATP Fermentation Pyruvate to Lactate or Ethanol (F8.3 p. 135) w/o O2 To Restore NADH: NAD ratio Copyright © 2005 Pearson Prentice Hall, Inc.

Glycolysis & Fermentation (cytoplasm) glucose Glycolysis 2 ATP C C C 2 2 C C C lactate pyruvate or 2 C C + 2 C Figure :8-1 top Title: A summary of glucose metabolism top Caption: Refer to this diagram as we progress through the reactions of glycolysis (in the fluid portion of the cytoplasm) and cellular respiration (in the mitochondria). The breakdown of glucose occurs in stages, with energy captured in ATP along the way. Most ATP is produced in the mitochondria. Fermentation ethanol CO2 C 2 CO2

Glycolysis & Cellular Respiration Glucose to Pyruvate Chemical Energy Released NADH & ATP Fermentation Pyruvate to Lactate or Ethanol (F8.3 p. 135) w/o O2 To Restore NADH: NAD ratio All Biopolymers: Interconvertable (not all reversible – N for aas) Can Yield Energy (FE8.2 p. 136) Copyright © 2005 Pearson Prentice Hall, Inc.

Glycolysis Krebs cycle Electron transport chain (cytoplasm) complex fats complex carbohydrates proteins glucose glycerol amino acids Glycolysis fatty acids pyruvate acetyl CoA Krebs cycle Figure: E8-2 Title: How various nutrients yield energy and can be interconverted Caption: Metabolic pathways allow interconversion of fats, proteins, and carbohydrates via intermediate molecules formed along the same pathways that break down glucose. Blue arrows show breakdown of these substances to provide energy. Red arrows show that these molecules may also be synthesized when there is an excess of the intermediates. electron carriers Electron transport chain synthesis breakdown (mitochondrion)

Glycolysis & Cellular Respiration Occurs in Four Steps (F8.1 p. 133) Glycolysis Cellular Respiration in 3 Steps Transport into Mitochondrion Krebs Cycle Electron Transport Chain Copyright © 2005 Pearson Prentice Hall, Inc.

Figure :8-T1 Title: Summary of Glycolysis and Cellular Respiration of a Molecule of Glucose Caption:

Glycolysis & Cellular Respiration Pyruvate Transport to Mitochondrial Matrix (F8.3 p.140,F8.5 p.139) Summary Reaction: Pyruvate => AcCoA + Carbon Dioxide Copyright © 2005 Pearson Prentice Hall, Inc.

mitochondrion inner membrane intermembrane compartment outer membrane matrix glucose cristae Figure :8-4 top Title: Cellular respiration top Caption: Cellular respiration occurs in mitochondria, whose structure accommodates the compartmentalized reactions that occur there. Note that the glycolysis that precedes cellular respiration occurs outside the mitochondrion in the cytoplasmic fluid. Glycolysis 2 pyruvate coenzyme A (intermembrane compartment) Copyright © 2005 Pearson Prentice Hall, Inc.

intermembrane compartment inner membrane outer membrane matrix cristae mitochondrion inner membrane outer membrane matrix glucose cristae Glycolysis 2 pyruvate coenzyme A (intermembrane compartment) ATP ATP H+ acetyl CoA Figure :8-4 Title: Cellular respiration Caption: Cellular respiration occurs in mitochondria, whose structure accommodates the compartmentalized reactions that occur there. Note that the glycolysis that precedes cellular respiration occurs outside the mitochondrion in the cytoplasmic fluid. CO2 (cytoplasm) H+ H+ ADP ATP Krebs cycle H+ (inner membrane) H2O 1/2 O2 H+ 2e– H+ 2 H+ H+ (matrix) H+ energized electron carriers Electron transport chain CO2 2e– (outer membrane) depleted carriers

Glycolysis & Cellular Respiration Krebs Cycle Summary Reaction: AcCoA + FAD + NAD => CO2 + FADH + NADH Copyright © 2005 Pearson Prentice Hall, Inc.

ATP ATP H+ acetyl CoA CO2 (cytoplasm) H+ H+ ADP ATP Krebs cycle (inner membrane) H+ H2O 1/2 O2 H+ 2e– H+ 2 H+ H+ energized electron carriers (matrix) H+ Figure :8-4 bottom Title: Cellular respiration bottom Caption: Cellular respiration occurs in mitochondria, whose structure accommodates the compartmentalized reactions that occur there. Note that the glycolysis that precedes cellular respiration occurs outside the mitochondrion in the cytoplasmic fluid. CO2 Electron transport chain 2e– (outer membrane) depleted carriers

C C C C C C C Formation of acetyl CoA 3 NADH 3 NAD+ FAD FADH2 CO2 coenzyme A coenzyme A _ C C CoA Krebs cycle C C C 2 C CO2 acetyl CoA pyruvate NAD+ NADH ADP Figure :8-5 Title: The reactions in the mitochondrial matrix Caption: 1 Pyruvate reacts with CoA, forming CO2 and acetyl CoA. During this reaction, an energetic electron is added to NAD+ to form NADH. When acetyl CoA enters the Krebs cycle 2, CoA is released. One set of the reactions in the cycle produces three NADH, one FADH2, two CO2, and one ATP for each acetyl CoA. Because each glucose molecule yields two pyruvates, the total energy harvest per glucose molecule in the matrix is two ATP, eight NADH, and two FADH2. ATP

Glycolysis & Cellular Respiration Electron Transport Chain (F8.6 pp. 141 & 2) Energy of NADH & FADH => Proton Gradient Chemiosmotic ATP Synthesis Oxygen Consumed (low energy e-“dump”) Water Formed Summary Reaction FADH + NADH + O2 => H2O + ATP Copyright © 2005 Pearson Prentice Hall, Inc.

(intermembrane compartment) (matrix) FADH2 1/2 O2 + 2H+ NADH NAD+ FAD 2e– 2e– H2O electron carriers (inner membrane) Figure :8-6 Title: The electron transport chain of mitochondria Caption: 1 NADH and FADH2 donate their energetic electrons to the carriers of the transport chain. 2 As the electrons pass through the transport chain, some of their energy is used to pump hydrogen ions from the matrix into the intermembrane compartment. This creates a hydrogen ion gradient that is used to drive ATP synthesis. 3 At the end of the electron transport chain, the energy-depleted electrons combine with oxygen and hydrogen ions in the matrix to form water. Question How would the rate of ATP production be affected by the absence of oxygen? H+ H+ H+ energy to drive ATP synthesis (intermembrane compartment)

H+ ion channel within ATP-synthesizing enzyme (matrix) electron transport chain (inner membrane) Figure: 8-UN3 Title: Anatomy of the mitochondrial membrane (intermembrane compartment) (outer membrane) (cytoplasm)

H2O 2 H+ 1/2 O2 NAD+ NADH H+ H+ 2e– H+ H+ H+ Figure: 8-UN4 Title: Pumping hydrogen ions across the inner membrane H+ H+ H+

H+ ADP ATP (low H+ concentration) H+ H+ H+ (high H+ H+ concentration) Figure: 8-UN5 Title: ATP synthesis in the mitochondria