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Enduring Understanding: Growth, reproduction and maintenance of the organization of living systems require free energy and matter. Essential Knowledge 2.A.2: Organisms capture and store free energy for use in biological processes.
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Enduring Understanding: Growth, reproduction and maintenance of the organization of living systems require free energy and matter Essential Knowledge 2.A.2: Organisms capture and store free energy for use in biological processes
Cellular respiration in eukaryotes involves a series of coordinated enzyme-catalyzed reactions that harvest free energy from simple carbohydrates • What happens to pyruvate after glycolysis? • Pyruvate is transported from the cytoplasm to the mitochondrion via a transport protein. • Pyruvate’s carboxyl group (COO-), which is already fully oxidized, is removed as CO2 • The remaining 2 carbon fragment is oxidized, forming a 2 C compound called acetate and reducing NAD+ to NADH + H+ • Acetate joins with Coenzyme-A, which makes it very reactive, forming Acetyl Co-A
CYTOSOL MITOCHONDRION NAD+ NADH + H+ 2 1 3 Acetyl CoA Coenzyme A Pyruvate CO2 Transport protein
Cellular respiration in eukaryotes involves a series of coordinated enzyme-catalyzed reactions that harvest free energy from simple carbohydrates • Where does the Krebs Cycle take place? • The matrix of the mitochondria • When Acetyl Co-A enters the Krebs Cycle, what does it join with? • It joins with OAA (oxaloacetate). The 2 carbons originally from Pyruvate (and glucose) join with the 4 carbons of OAA to form 6 carbon Citrate.
Cellular respiration in eukaryotes involves a series of coordinated enzyme-catalyzed reactions that harvest free energy from simple carbohydrates • What happens in the Krebs cycle? • Through a series of enzyme catalyzed reactions the remaining 2 carbons from pyruvate (originally from glucose) are oxidized and expelled as CO2. 3 NAD+ are reduced to form 3 NADH + 3H+and 1 FAD is reduced to form 1 FADH2. Indirectly 1 ATP is formed. • How is ATP formed during the Krebs Cycle? • Substrate level phosphorylation
Summary of products from 1 turn of the Krebs Cycle: Acetyl CoA CoA—SH NADH H2O 1 +H+ 2 CO2 3NADH + H+ 1FADH2 1ATP NAD+ Oxaloacetate 8 2 Malate Citrate Isocitrate NAD+ Citric acid cycle NADH 3 + H+ 7 H2O CO2 Fumarate CoA—SH -Keto- glutarate 4 6 CoA—SH 5 FADH2 CO2 NAD+ FAD Succinate NADH P i + H+ Succinyl CoA GDP GTP ADP ATP
Pyruvate CO2 NAD+ CoA Summary of products from the end of glycolysis thru the Krebs Cycle per glucose molecule: NADH + H+ Acetyl CoA CoA CoA 6 CO2 8 NADH + H+ 2 FADH2 2ATP Citric acid cycle 2 CO2 FADH2 3 NAD+ NADH 3 FAD + 3 H+ ADP + P i ATP
Enduring Understanding 4.A: Interactions within biological systems lead to complex properties (side bar) • Essential Knowledge 4.A.2:The structure and function of subcellular components, and their interactions, provide essential cellular processes. • How do mitochondria specialize in energy capture and transformation? • Mitochondria have a double membrane that allows compartmentalization within the mitochondria and is important to its function • Matrix (within the inner membrane) • Intermembrane Space (between the inner & outer membranes) • The outer membrane is smooth, but the inner membrane is highly convoluted, forming folds called cristae • Cristae contain enzymes important to ATP production; cristae also increase the surface area for ATP production
Intermembrane space Outer membrane Free ribosomes in the mitochondrial matrix Inner membrane Cristae Matrix 0.1 µm
The electron transport chain captures free energy from electrons in a series of coupled reactions that establish an electrochemical gradient across membranes. • Where is the electron transport chain of cellular respiration? • The Cristae (inner member of mitochondria) • In prokaryotic organisms it is located in the plasma membrane
The electron transport chain captures free energy from electrons in a series of coupled reactions that establish an electrochemical gradient across membranes. • What happens at the electron transport chain? • Electrons delivered by NADH and FADH2 are passed thru a series of electron acceptors as they move toward the terminal electron acceptor, oxygen. • What happens as electrons move through the electron transport chain? • The energy released by passage of electrons from one electron carrier to the next is used to pump H+ from the matrix into the intermembrane space. (In prokaryotes H+ is pumped outside the plasma membrane.) • This creates a gradient of H+ across the membrane called a proton-motive force.
INTERMEMBRANE SPACE The electron transport chain captures free energy from electrons in a series of coupled reactions that establish an electrochemical gradient across membranes. H+ Stator • How does the proton gradient (H+) produce ATP? • The energy stored in the proton gradient is released as H+ move back across the cristae through H+ channels provided by ATP synthases- chemiosmosis Rotor Internal rod Cata- lytic knob ADP + ATP P i MITOCHONDRIAL MATRIX
H+ H+ H+ H+ Protein complex of electron carriers Cyt c V Q ATP synthase H2O 2 H+ + 1/2O2 FADH2 FAD NAD+ NADH ADP + ATP P i (carrying electrons from food) H+ Chemiosmosis Electron transport chain 1 2 Oxidative phosphorylation
The electron transport chain captures free energy from electrons in a series of coupled reactions that establish an electrochemical gradient across membranes. • Chemiosmosis couples the electron transport chain to ATP Synthesis… • Electron Transport Chain: Electron transport and pumping protons (H+), which create an H+ gradient across the membrane • Chemiosmosis – ATP synthesis powered by the flow of H+ back across the membrane
Electron shuttles span membrane MITOCHONDRION CYTOSOL 2 NADH or 2 FADH2 2 NADH 6 NADH 2 FADH2 2 NADH Oxidative phosphorylation: electron transport and chemiosmosis Glycolysis Citric acid cycle 2 Acetyl CoA 2 Pyruvate Glucose + 2 ATP + 2 ATP + about 32 or 34 ATP About 36 or 38 ATP Maximum per glucose:
