Where did Bruce Lee get all that energy from? Chapter 3 Cellular Respiration Where did Bruce Lee get all that energy from?

1 36 What is it? Cellular respiration O2 An aerobic process (requires oxygen) Uses chemical energy from glucose to make ATP Chemical energy is now stored in ATP for use throughout the body O2 glucose 1 ATP 36 Cellular resp.

Four Main Stages Glycolysis Anaerobic In cytosol breaks glucose (6C) into 2 pyruvate molecules (3C) releases ATP Transition reaction (oxidative decarboxylation) Pyruvate converted to acetyl CoA releasing CO2 Kreb’s Cycle Within mitochondrial matrix Oxidize each acetyl CoA to CO2 Releases ATP and co-enzymes (NADH, FADH2) Electron Transport Chain Along the inner mitochondrial membrane Uses high energy electrons from NADH and FADH2 to create an electrochemical proton (H+) gradient which powers ATP synthesis

Fermentation When oxygen is NOT available, cells can metabolize pyruvate (derived from glucose) by the process of fermentation. Two Types (i) alcohol fermentation: pyruvate (3C) converted (reduced) to ethyl alcohol (2C) and CO2; occurs in yeast cells (ii) lactic acid fermentation: pyruvate(3C) converted (reduced) to lactic acid (3C) in muscle cells

glucose + O2  CO2 + H2O + energy Cellular Respiration General Formula O2 glucose CO2 H2O H+ Energy glucose + O2  CO2 + H2O + energy This process begins with glucose. Once it enters a cell, the process of glycolysis begins immediately in the cytoplasm where enzymes are waiting.

Glycolysis (I) Overview This is the investment period of glycolysis ATP is USED in order to “activate” glucose This is accomplish by an enzyme mediated process called: substrate level phosphorylation Involving the transfer of a phosphate group

Numbering the Carbons of Glucose In order to keep track of how glucose is modified and rearranged during glycolysis we number each carbon C O 6 5 glucose 1 4 3 2

Glycolysis (I) glucose glucose-6-phosphate fructose-6-phosphate fructose-1-6-bisphosphate 2 molecules of PGAL (glyceraldehyde-3-phosphate) P P P C O C O P C O P P P C O P P C P C P

Glycolysis (I) glucose glucose-6-phosphate fructose-6-phosphate ATP glucose glucose-6-phosphate fructose-6-phosphate fructose-1-6-biphosphate 2 molecules of PGAL (glyceraldehyde-3-phosphate) activation ADP P C O isomerization C O P ATP activation ADP C O P P cleavage C P C P

Investment Glycolysis (I) 1. Activation: Phosphate from ATP is added to glucose to form glucose-6-phosphate. [substrate-level phosphorylation] 2. Isomerization: Glucose-6-phosphate is rearranged to form fructose-6-phosphate. 3. Activation: A second phosphate from another ATP is added to form fructose-1,6-bisphosphate. [substrate-level phosphorylation] 4. Cleavage: The unstable fructose-1,6-bisphosphate splits into phosphoglyceraldehyde (PGAL) and dihydroxyacetone phosphate (DHAP). Investment

Glycolysis (II) Overview This is the pay-off period of glycolysis ATP and NADH (a high energy molecule) are PRODUCED during glycolysis II By the end of glycolysis II, glucose has been broken down from 6 carbons to a 3 carbon compound called Pyruvate (pyruvic acid)

Glycolysis (II) PGAL PGAP PGA PEP Pyruvate NAD NAD NADH NADH H2O H2O H Pi Pi NADH NADH C P P P P P P C P P C P H2O H H2O H C P P P P P P C

isomerization / dehydration Glycolysis (II) PGAL PGAP PGA PEP Pyruvate C P C P NADH activation / redox NADH C P P ATP ATP dephosphorylation C P P H2O H isomerization / dehydration H2O H C P C P ATP ATP dephosphorylation P C

Pay-off Glycolysis (II) 5. Activation/Redox: Each molecule of PGAL is oxidized by NAD and gains a phosphate to form 1,3-bisphosphoglycerate (PGAP). 6. Phosphorylation: Each PGAP loses a phosphate to ADP resulting in 2 ATP and two 3-phosphoglycerate molecules (3-PGA).[substrate-level phosphorylation] 7. Isomerization: Both 3-PGA molecules are rearranged to form 2-phosphoglycerate (2-PGA). [note: the text does not distinguish between 3-PGA and 2-PGA, but refers to both as PGA] 8. Dehydration: Both 2-PGA molecules are oxidized to phosphoenol pyruvate (PEP) by the removal of water. 9. Phosphorylation: Each PEP molecule loses a phosphate to ADP resulting in 2 more ATP and 2 molecules of pyruvate. [substrate-level phosphorylation] Pay-off

2 2 The Result Energy in Glycolysis Used 2 ATP Made 4 ATP Net Gain: 4ATP – 2ATP = And 1 3 5 ATP 2 6 9 NADH 2 (high energy molecule)

Glycolysis: overall reaction C6H12O6 + 2ADP + 2P + 2NAD+  2C3H4O3 + 2NADH + 2ATP glucose (6C) pyruvate (3C) Notice: There is no oxygen used in glycolysis. It is an anaerobic process O2

The Power House! In the cytosol, for each glucose molecule consumed, only 2 ATP were produced This means that 34 more ATP are made in the mitochondria! How do we get in there and what happens inside!? nucleus cytosol ATP ATP mitochondria ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP ATP

Inside the Mitochondria

Inside the Mitochondria outer membrane: contains transport protein porin, which affects permeability inner membrane: contains the phospholipid cardiolipin that makes membrane impermeable to ions, a condition which is required for ATP production intermembrane space: fluid-filled area containing enzymes and hydrogen ions matrix: location of Kreb’s Cycle cristae: folds of the inner membrane where ETC enzymes are found

Transition Reaction C – C – C mitochondrion Intermembrane space pyruvate multi-enzyme pyruvate dehydrogenase complex

Transition Reaction 1. Decarboxylation CO2 C – C – C C – C mitochondrion Intermembrane space 1. Decarboxylation CO2 C – C – C pyruvate C – C

Transition Reaction NAD+ NADH 2. Oxidation C – C C – C mitochondrion Intermembrane space NAD+ NADH 2. Oxidation C – C C – C

Transition Reaction C – C 3. Attachment mitochondrion Intermembrane space C – C 3. Attachment CoA

Transition Reaction C – C 3. Attachment mitochondrion Intermembrane space Acetyl CoA C – C CoA 3. Attachment

Steps A and B together are referred to as oxidative decarboxylation Transition Reaction Decarboxylation (-CO2) of pyruvate leaving a 2C molecule Oxidation by NAD+ forming an acetate molecule. Attachment of coenzyme A forming acetyl coA. Steps A and B together are referred to as oxidative decarboxylation

1 1 Transition Reaction NADH In the transition reaction, for each molecule of pyruvate: CO2 1 is released and NADH 1 is produced

X2 2 1 Transition Reaction NADH NADH are released and are prodcued Remember: There are 2 pyruvates produced for each glucose. Therefore, for each glucose: CO2 2 are released and NADH are prodcued CO2 1 is released and NADH is produced X2

Krebs Cycle 1. Acetyl coA breaks into coenzyme A, which is recycled, and an acetyl group (2C) which joins to oxaloacetate (4C) forming citrate (6C). 2. Citrate (6C) converts to isocitrate (6C). 3. Isocitrate (6C) loses CO2 and is then oxidized by NAD forming alpha-ketoglutarate (5C). [oxidative decarboxylation] 4. Alpha-ketoglutarate (5C) is converted to succinyl-coA (4C) in 3 steps: (i) loss of CO2 (ii) oxidation by NAD+ (iii) attachment of coenzyme A

Krebs Cycle 5. Succinyl coA (4C) is converted to succinate (4C) in the following way: - coenzyme A breaks off and is recycled; phosphate attaches temporarily to succinate and is then transferred to GDP forming GTP; GTP transfers phosphate to ADP forming ATP (substrate level phosphorylation). 6. Succinate (4C) is oxidized by FAD to form fumarate (4C). 7. Water is added to fumarate (4C) to form malate (4C). 8. Malate (4C) is oxidized by NAD+ to form oxaloacetate, which is regenerated to begin the cycle again.

Krebs Cycle Transition reaction Krebs Cycle

Krebs Cycle In the Krebs Cycle for each molecule of pyruvate: CO2 2 are released and NADH 3 ATP 1 FADH2 1 are produced

X2 4 6 2 2 3 1 Krebs Cycle NADH FADH2 NADH FADH2 Remember: There are 2 pyruvates produced for each glucose. Therefore, for each glucose: CO2 4 are released NADH 6 and FADH2 2 ATP are produced CO2 2 are released NADH 3 and FADH2 1 ATP are prodcued X2

1 2 6 The Story So Far C – C – C (6C) (3C) (1C) Tracking carbon: glucose 1 C – C – C pyruvate 2 CO2 6 (6C) (3C) (1C)

2 2 2 6 4 10 2 The Story So Far Total Glycolysis Tracking High Energy Molecules Metabolic Process ATP Produced High Energy Molecules Glycolysis Transition Reaction (x2) (oxidative decarboxylation) Krebs Cycle (x2) Total ATP 2 NADH in cytosol NADH 2 ATP 2 NADH 6 FADH2 ATP 4 NADH 10 FADH2 2

Using the High Energy Molecules NADH and FADH2 have gained high energy electrons These electrons are donated to electron carrier proteins in the Electron Transport Chain (ETC). The energy from these electrons is then used to pump protons (H+) into the intermembrane space of the mitchondria

Electron Transport Chain not part of the ETC C Cristae Q NADH reductase Co-enzyme Q Cytochrome b1c1 Cytochrome c Cytochrome c oxidase ATP Synthase Electron Carriers: 1. NADH reductase [protein] 2. Coenzyme Q [non-protein] 3. Cytochrome b1 c1 4. Cytochrome c 5. Cytochrome c oxidase [protein]

Electron Transport Chain Cristae Q To pass electrons along ETC, each carrier is reduced (gains electrons) then oxidized (donates electrons) Curious? Where do these electrons come from? Electrons come from hydrogen atoms (H atoms separate into electrons and protons)

Electron Transport Chain Cristae Q NAD+ NADH NADH donates a pair of electrons to NADH reductase electrons continue along ETC via sequential oxidations and reductions

Electron Transport Chain Cristae Q FADH2 FADH2 donates a pair of electrons to coenzyme Q electrons also continue along ETC

Electron Transport Chain Cristae Q FADH2 donates a pair of electrons to coenzyme Q electrons also continue along ETC

For each NADH, 6 H+ are pumped across the mitochondrion inner membrane Cristae Q NAD+ H+ H+ H+ H+ H+ H+ H+ NADH H+ H+ H+ H+ H+ H+ For each NADH, 6 H+ are pumped across the mitochondrion inner membrane

For each NADH, 6 H+ are pumped across the mitochondrion inner membrane Cristae Q H2O H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ O2 For each NADH, 6 H+ are pumped across the mitochondrion inner membrane Oxygen is the final electron acceptor and is converted to H2O

H+ H+ H+ C Cristae Q H2O H+ H+ H+ H+ H+ H+ H+ FADH2 H+ H+ H+ H+ O2 For each FADH2, 4 H+ are pumped across the mitochondrion inner membrane

The electrochemical proton gradient High Proton Concentration H+ H+ Gradient C Cristae Q H+ Low Proton Concentration H+ H+ H+ H+ H+ The electrochemical proton gradient (sometimes referred to as the proton motive force)

H+ H+ H+ H+ H+ H+ H+ C Cristae Q ATP H+ H+ H+ H+ H+ H+ Using the energy stored in the proton gradient, ATP is generated using oxidative phosphorylation: formation of ATP coupled to oxygen consumption Using the electrochemial proton gradient to produce ATP from ADP is called chemiosmosis

H+ H+ H+ H+ H+ H+ H+ C Cristae Q ATP ATP ATP H+ H+ H+ H+ H+ H+ 1 ATP is generated for each proton pair flowing through ATP synthase. Pumps H+ 6 3 NADH

H+ H+ H+ H+ H+ H+ H+ C Cristae Q ATP ATP H+ H+ H+ H+ H+ H+ 1 ATP is generated for each proton pair flowing through ATP synthase. Pumps H+ 4 2 FADH2

ATP synthase works a bit like a water mill

The WHOLE process… Cristae C Q H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+

The WHOLE process… Cristae NAD+ NADH C Q H+ H+ H+ H+ H+ H+ H+ H+ H+ H+

The WHOLE process… Cristae C H2O O2 Q H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+

The WHOLE process… Cristae C ATP ATP ATP Q H+ H+ H+ H+ H+ H+ H+ H+ H+

The WHOLE process… Cristae C ATP ATP ATP Q H+ H+ H+ H+ H+ H+ H+ H+ H+

Remember: BEFORE the ETC we had… Summing up ATP Remember: BEFORE the ETC we had… Metabolic Process ATP Produced High Energy Molecules Glycolysis Transition Reaction (x2) (oxidative decarboxylation) Krebs Cycle (x2) Total ATP 2 NADH in cytosol NADH 2 ATP 2 NADH 6 FADH2 ATP 4 NADH 10 FADH2 2

In the Electron Transport Chain Summing up ATP In the Electron Transport Chain Molecules from High Energy Molecules ATP produced in ETC Glycolysis Transition Reaction (x2) (oxidative decarboxylation) Krebs Cycle (x2) Total NADH 2 ATP 4 in cytosol NADH 2 ATP 6 NADH 6 FADH2 2 ATP 22 10 FADH2 2 ATP 32 NADH

2 2 4 + From Glycolysis 2 2 6 6 2 22 10 2 34 32 Summing up ATP Total IN TOTAL Molecules from High Energy Molecules ATP produced in ETC Glycolysis Transition Reaction (x2) (oxidative decarboxylation) Krebs Cycle (x2) Total ATP 2 NADH 2 ATP 4 in cytosol + From Glycolysis ATP 2 NADH 2 ATP 6 NADH 6 FADH2 2 ATP 22 10 FADH2 2 ATP 34 ATP 32 NADH

2 2 4 + From Krebs Cycle 2 2 6 6 2 22 2 10 2 36 34 Summing up ATP IN TOTAL Molecules from High Energy Molecules ATP produced in ETC Glycolysis Transition Reaction (x2) (oxidative decarboxylation) Krebs Cycle (x2) Total ATP 2 NADH 2 ATP 4 in cytosol + From Krebs Cycle ATP 2 NADH 2 ATP 6 NADH 6 FADH2 2 ATP 22 ATP 2 10 FADH2 2 ATP 36 ATP 34 NADH

glucose + oxygen carbon dioxide + water + energy Overall Reaction glucose 1 CO2 6 glucose CO2 NAD+ 10 FAD 2 NADH 10 FADH2 2 NAD+ 10 FAD 2 Catalysts ATP 36 Energy H2O H+ H2O H+ O2 O2 glucose + oxygen carbon dioxide + water + energy

glucose + oxygen carbon dioxide + water + energy Overall Reaction Phase (location) Glycolysis (cytosol) Transition Reaction (mito.) Kreb’s Cycle (mito.) ETC (mito.) glucose 1 CO2 6 some NAD+ 10 FAD 2 ATP 36 some H2O H+ O2 glucose + oxygen carbon dioxide + water + energy