Energy Flow Chapter 7 Cellular Respiration hotosynthesis uses solar energy to produce glucose and O from CO and H O Cellular respiration makes and consumes O during the oxidation of glucose to CO and H O ECOSYSTEM CO H O Sunlight energy hotosynthesis in chloroplasts Cellular respiration in mitochondria (for cellular work) Glucose + + O Heat energy Cellular Respiration: Overview 1. reparatory Reaction ( yruvate grooming ). Citric Acid Cycle Cellular Respiration Cellular Respiration occurs in three stages Mitochondrion Cytosol Glucose and other fuel molecules yruvate yruvate oxidation Acetyl- Electrons carried by and FADH Substrate-level phosphorylation Substrate-level phosphorylation 3. Electron Transport Chain Electron transfer system and oxidative phosphorylation Oxidative phosphorylation
Cellular Respiration is compartmentalized Cytoplasm 1.. reparatory reaction glucose pyruvate 4 AD 4 total AD net gain 3. and FADH 4. chain + AD + 3 AD 3 = 36 or 38 Breakdown of glucose to two molecules of pyruvate One six-carbon molecule into two threecarbon molecules Oxidation by removal of hydrogens releases enough energy to make two Outside the Mitochondria: Energy-Investment Steps Steps glucose - 1. Two are used to activate glucose. AD AD Takes place in the cytoplasm Does not require oxygen Energy-Harvesting Steps G3 G3. A resulting C 6 molecule breaks down into C 3 molecules. 3. takes an becoming, with addition of a second phosphate to the sugar. Energy-Investment Steps Energy from two is used to activate glucose Glucose is split into two 3-carbon G3 (glyceraldehyde 3-phosphate) molecules G3 is oxidized to yruvate, four are produced + + BG AD 3G H O E AD (net gain) pyruvate BG 3G E pyruvate AD H O AD 4. Removal of high-energy phosphate from BG by AD produces and 3G molecules. 5. Oxidation of 3G by removal of water results in high-energy E molecules. 6. Removal of high-energy phosphate from E by AD produces and pyruvate molecules. b.
yruvate is groomed to move into the mitochondria Inside the Mitochondria Cytoplasm reparatory reaction glucose pyruvate AD and FADH chain and Final reactions occur inside mitochondria reparatory Reaction Reactions occur in matrix of mitochondria roduces Acyetyl~, the molecule that will enter the citric acid 3C pyruvate is converted to C acetyl group 4 AD 4 total net AD 3 AD 3 Inside the Mitochondria Acetyl group attached to to become acetyl~ Carbon dioxide is produced Hydrogen atoms are removed from pyruvate and picked up to form This reaction occurs twice per glucose Citric Acid Cycle Occurs in the matrix of the mitochondria Acetyl is converted to citric acid and enters the Cyclical series of oxidation reactions that produces one and carbon dioxide per turn turns twice because two acetyl s are produced per glucose pyruvate + acetyl + carbon dioxide
Citric Acid Cycle (1) and FADH 1. The C acetyl group combines with a molecule to produce citrate, a C 6 molecule. glucose pyruvate reparatory reaction Matrix chain and reparatory reaction acetyl AD 4 AD 4 total net AD 3 AD 3 Citric Acid Cycle () Citric Acid Cycle (3) 1. The C acetyl group combines with a molecule to produce citrate, a C 6 molecule. reparatory reaction acetyl citrate C 5 CO. Oxidation reactions produce two. 1. The C acetyl group combines with a molecule to produce citrate, a C 6 molecule. reparatory reaction acetyl citrate C 5 CO. Oxidation reactions produce two. 3. The loss of two CO results In a new molecule. CO 4. One is produced by substrate-level synthesis.
Citric Acid Cycle (4) 1. The C acetyl group combines with a molecule to produce citrate, a C 6 molecule. citrate CO. Oxidation reactions produce two. inputs outputs acetyl groups 4 CO reparatory reaction 5. Additional oxidation reactions produce an FADH and another and regenerate original molecule. acetyl FADH FAD C 5 CO 3. The loss of two CO results In a new molecule. 4. One is produced by substrate-level synthesis. 6 FAD AD + 6 FADH Inside the Mitochondria: ETC Electron Transport Chain Series of molecules Electrons passed from one to another As the s move from a higher energy state to a lower one, energy is released to make Under aerobic conditions 3-34 per glucose molecule can be produced Inside the Mitochondria: ETC Electron Transport Chain Located in inner mitochondrial membrane High-energy s enter the system and low-energy s leave the system Two-s per and FADH enter the transport chain Electrons are passed to a series of s called cytochromes Each reduced and then oxidized
high-energy s energy for synthesis of Inside the Mitochondria: Chemiosmosis and Oxidative hosphorylation transport chain low-energy s As s pass from one to another, energy is captured and stored as a hydrogen ion concentration gradient Oxygen combines with hydrogen ions to form water and FAD are red to pick up more s from glycolysis, prep reaction, and citric acid + H + AD + and FADH FADH FAD + H + glucose pyruvate reparatory reaction chain and AD + AD 4 AD 4 total net ADT 3 or AD 34 3 or 34 AD + H + 1 O H O
pyruvate and FADH glucose Electron Transport Chain chain protein complex chain and reparatory reaction AD 4 AD 4 total net ADT 3 or AD 3 or 34 34 cristae + NAD+ + e- AD + FADH FAD + NAD+ e-- FADH FAD + + e intermembrane space matrix O AD + HO 1 matrix AD + channel protein synthase complex intermembrane space AD + H O Total of 4 by substrate-level synthesis net from glycolysis from citric acid 3-34 produced by transport chain and net glycolysis + + 6 + FADH 4 or 6 6 18 4 subtotal 3 pyruvate acetyl CO chain Energy yield glucose Cytoplasm Inside the Mitochondria Cellular Respiration, Efficiency Mitochondrion 1 O 4 CO Some cells have to pay to pump from glycolysis into mitochondria 6 O subtotal 4 36 or 38 total 6 HO
Inside the Mitochondria Fermentation Efficiency of Cellular Respiration The difference in energy content of reactants (glucose and oxygen) and products (carbon dioxide and water) is 686 kcal phosphate bond has 7.3 kcal of energy 36 are produced in respiration 36 X 7.3 = 63 kcal 63/686 = 39% efficiency of energy capture The rest of the energy is lost as heat Fermentation Occurs when O is not available Animal cells convert pyruvate to lactate Other organisms convert pyruvate to alcohol and CO Fermentation regenerates which keeps glycolysis and substrate-level synthesis going glucose Fermentation - AD G3 Advantages and Disadvantages rovides a rapid burst of + 4 4 BG 4 AD pyruvate rovides a low but continuous supply of when oxygen is limited and only glycolysis can function Lactate is potentially toxic to muscles, lowering ph and causing fatigue or CO (net gain) lactate alcohol