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Aerobic Respiration. Section 9:2. Aerobic Respiration – Oxygen Present. Occurs in the mitochondria of eukaryotes and the cytosol of prokaryotes. Pyruvic acid, from Glycolysis, diffuses in from the cytosol to the mitochondrial matrix . The space inside the inner membranes.
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Aerobic Respiration Section 9:2
Aerobic Respiration – Oxygen Present • Occurs in the mitochondria of eukaryotes and the cytosol of prokaryotes. • Pyruvic acid, from Glycolysis, diffuses in from the cytosol to the mitochondrial matrix. • The space inside the inner membranes
inner compartment outer compartment cytoplasm outer mitochondrial membrane inner mitochondrial membrane (see next slide) Fig. 7.5a, p. 114
Krebs Cycle • A biochemical pathway that breaks down a compound acetyl CoA, producing CO2, NADH, FADH, ATP and Citric Acid. • 5 steps to the Krebs Cycle
Aerobic Respiration – before Krebs Cycle (reparatory step) • Pyruvic acid joins with coenzyme A (CoA), no carbons, to form acetyl CoA – 2 carbons • CO2 is lost in this process and NAD is reduced to NADH and H+.
Step 1 • The 2-carbon acetyl CoA combines with a 4-carbon compound, oxaloacetic acid, to form a 6-carbon molecule, citric acid • This step regenerates co-enzyme A so it can return back to join with pyruvic acid.
PREPARATORYSTEPS pyruvate coenzyme A (CoA) NAD+ (CO2) NADH CoA Acetyl–CoA KREBS CYCLE CoA oxaloacetate citrate H2O NADH H2O NAD+ isocitrate malate NAD+ H2O NADH fumarate a-ketogluterate FADH2 CoA NAD+ FAD NADH succinate CoA succinyl–CoA Fig. 7.6, p. 115 ADP + phosphate group (from GTP) ATP
Step 2 • Citric acid releases a CO2 and a hydrogen to form a 5-carbon compound • NAD+(electron acceptor) accepts an H+ to become NADH and H+.
PREPARATORY STEPS pyruvate coenzyme A (CoA) NAD+ (CO2) NADH CoA Acetyl–CoA KREBS CYCLE CoA oxaloacetate citrate H2O NADH H2O NAD+ isocitrate malate NAD+ H2O NADH fumarate a-ketogluterate FADH2 CoA NAD+ FAD NADH succinate CoA succinyl–CoA Fig. 7.6, p. 115 ADP + phosphate group (from GTP) ATP
Step 3 • The 5-carbon compound releases CO2 and H+ to form a 4-carbon compound. • NAD+ is reduced again to NADH and One molecules of ATP is made
PREPARATORY STEPS pyruvate coenzyme A (CoA) NAD+ (CO2) NADH CoA Acetyl–CoA KREBS CYCLE CoA oxaloacetate citrate H2O NADH H2O NAD+ isocitrate malate NAD+ H2O NADH fumarate a-ketogluterate FADH2 CoA NAD+ FAD NADH succinate CoA succinyl–CoA Fig. 7.6, p. 115 ADP + phosphategroup (fromGTP) ATP
Step 4 • The 4-carbon compound releases hydrogen • The hydrogen forms with FAD+ to form FADH2. FAD is another electron acceptor.
PREPARATORY STEPS pyruvate coenzyme A (CoA) NAD+ (CO2) NADH CoA Acetyl–CoA KREBS CYCLE CoA oxaloacetate citrate H2O NADH H2O NAD+ isocitrate malate NAD+ H2O NADH fumarate a-ketogluterate FADH2 CoA NAD+ FAD NADH succinate CoA succinyl–CoA Fig. 7.6, p. 115 ADP + phosphate group (from GTP) ATP
Step 5 • The 4-carbon compound releases a hydrogen to REFORMoxaloacetic acid • NAD+ is reduced again to NADH and H+
PREPARATORY STEPS pyruvate coenzyme A (CoA) NAD+ (CO2) NADH CoA Acetyl–CoA KREBS CYCLE CoA oxaloacetate citrate H2O NADH H2O NAD+ isocitrate malate NAD+ H2O NADH fumarate a-ketogluterate FADH2 CoA NAD+ FAD NADH succinate CoA succinyl–CoA Fig. 7.6, p. 115 ADP + phosphate group (from GTP) ATP
Glycolysis, produces 2 NADH and 2 pyruvic acid, 2 ATP. • One molecule of glucose from glycolysis needs 2 turns of the Krebs to produce: • Summary: 10 NADH, 2 FADH, 4 ATP, 4 CO2. The 10 NADH and 2 FADH (both energy molecules) will drive the next stage of cellular respiration in the Electron Transport Chain.
Krebs Cycle conclusion • Location – Mitochondrial Matrix (space inside the inner membrane) • Function – Produce Citric Acid and CO2. • Reactants – Pyruvic Acid, Acetlyl-CoA, Oxaloacitic Acid, NAD, FAD, ADP and C0enzyme A. • Products – CO2 NADH, FADH, ATP and Citric acid.
Compounds and their # of carbon atoms • CO2 – 1 Oxaloactic Acid - 4 • RuBP – 5 Citric Acid - 6 • PGA – 3 Co-enzyme A - 0 • PGAL – 3 • Glucose – 6 • Pyruvic Acid – 3 • Lactic Acid – 3 • Ethyl Alcohol – 2 • Acetyl – CoA - 2
Cellular Respiration • The process that releases energy by breaking down glucose and other food molecules in the presence of oxygen.
Electron Transport Chain • A chemical reaction that uses high energy electrons made in the Krebs cycle to convert ADP into ATP. • Aerobic – means with oxygen • Anaerobic – means without oxygen
Electron Transport Chain • ATP is produced when NADH and FADH2 release hydrogen atoms, regenerating NAD+ and FAD+. • This occurs along the lining of the inner membranes of the mitochondria.
Steps of ETC • 1. Electrons from the hydrogens atoms of NADH and FADH are passed along a series of molecules, releasing energy along the way.
2. This released energy pumps protons from the matrix to the other side of the membrane. • This creates a concentration gradient across the inner membrane of the mitochondria.
OUTER COMPARTMENT NADH INNER COMPARTMENT Fig. 7.7a, p. 116
3. This high proton concentration gradient is what drives chemiosmosis ( ATP production) into the inner membrane. ATP synthase is located in the inner membrane. ATP is made as protons move down their concentration gradient in the mitochondria.
Oxygen’s Role • Oxygen is the final electron acceptor, accepting electrons from the last molecule in the ETC. • This allows ATP to continue to be synthesized. • Oxygen also accepts the hydrogen atoms from NADH and FADH. • This combination of electron, hydrogens and oxygen forms WATER!!!!! O2 + e- +H- = H2O
ATP NADH INNER COMPARTMENT ADP+Pi Fig. 7.7b, p. 116
Energy Yield • Per molecule of glucose, 36 ATP’s are produced. • 2 in Glycolysis, and 2 in Krebs and 32 in ETC. • C6H12O6 + 6O2 6CO2 + 6H2O + energy
1 Pyruvate from cytoplasm enters inner mitochondrial compartment. OUTER COMPARTMENT 4 As electrons move through the transport system, H+ is pumped to outer compartment. NADH 3 NADH and FADH2 give up electrons and H+ to membrane-bound electron transport systems. acetyl-CoA NADH Krebs Cycle NADH ATP ATP 5 Oxygen accepts electrons, joins with H+ to form water. ATP 2 Krebs cycle and preparatory steps: NAD+ and FADH2 accept electrons and hydrogen stripped from the pyruvate. ATP forms. Carbon dioxide forms. ATP free oxygen ADP + Pi INNER COMPARTMENT 6 Following its gradients, H+ flows back into inner compartment, through ATP synthases. The flow drives ATP formation. Fig. 7.5b, p. 114
Krebs Cycle and ETC. • Both the Krebs Cycle and the Electron Transport chain can not proceed without the presence of • O2 • H2O • CO2
Conclusion of Electron Transport Chain • Location – Lining of the inner membrane of the mitochondria. • Function – Produce ATP and water • Reactants – NADH, FADH, ADP and O2. • Products – NAD, FAD, ATP and Water
Order of processes in Cellular Respiration. • 1. Glycolysis • 2. Krebs cycle • 3. Electron Transport Chain
# of carbon atoms in compounds • CO2 – 1 PGA - 3 • RuBP – 5 PGAL - 3 • Glucose – 6 • Oxaloacitic Acid – 4 • Acetyl Co-A – 2 • Pyruvic Acid – 3 • Citric Acid – 6 • Lactic Acid – 3 • Ethyl Alcohol – 2 • Co-enzyme A - 0