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Cellular Respiration (Chapter 9). Energy. Plants, algae & some bacteria Convert radiant energy (sun) into chemical energy (glucose). Harvest Energy. All activities an organism performs requires energy. Catabolism. Enzymes break down substances Harvest energy from C-H bonds
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Energy • Plants, algae & some bacteria • Convert radiant energy (sun) into chemical energy (glucose)
Harvest Energy • All activities an organism performs requires energy
Catabolism • Enzymes break down substances • Harvest energy from C-H bonds • Or other chemical bonds Organic compounds + oxygen ⇨ Carbon Dioxide + water + energy
Cellular respiration • Aerobic respiration • Chemical energy is harvested from food • Presence of oxygen • Anaerobic respiration • Process occurs without oxygen • Fermentation
Anaerobic • Glucose to lactate (muscle cells) • Glucose to alcohol (yeast cells) • Does not yield as much energy
Cellular respiration C6H12O6 + 6 O2 ---> 6 CO2 + 6 H2O + ATP
Cellular Respiration • Exergonic • -686kcal/mole (-2,870kJ/mole) • Redox reaction • Glucose is oxidized, oxygen is reduced • Energy stored in glucose makes ATP • 38 ATP generated • ATP stores energy for use in cellular functions
Vocabulary (Cell respire) NAD/NADH FAD ETC Phosphorylation Chemiosmosis ATP Synthase
NAD & NADH • NAD: • Nicotinamide adenine dinucleotide • NAD+ oxidized form • NADH reduced form • NAD+ traps electrons from glucose • Function as energy carrier
NAD & NADH • Dehydrogenase (enzyme) • Removes a pair of hydrogen atoms from glucose • Transfers one proton and 2 electrons to NAD+ H-C-OH + NAD+⇨ -C=O + NADH + H+ • Used to make ATP
FAD • Flavin adenine dinucleotide • Transfers electrons
Electron transport chain • Located inner membrane of mitochondria • Plasma membrane (prokaryotes) • Series of molecules (mostly proteins)
Electron transport chain • Electrons fall to oxygen • In a series of energy releasing steps • High potential energy to low • Energy released generates ATP
Electron transport chain 1/2 O2 + 2 H (from food via NADH) Controlled release of energy for synthesis of ATP 2 H+ + 2 e– ATP ATP Electron transport chain Free energy, G ATP 2 e– 1/2 O2 2 H+ H2O
Phosphorylation • Addition of a phosphate group to a molecule • ATP is formed by a phosphorylation reaction • 1. Substrate-level phosphorylation • 2. Oxidative phosphorylation
Substrate phosphorylation • Enzyme transfers a phosphate from a organic substrate molecule • ADP to make ATP • Direct formation • Glycolysis and Krebs cycle
Oxidation phosphorylation • Energy from electron transport chain • Synthesis ATP • Adds an inorganic phosphate to ADP
Chemiosmosis • Energy-coupling mechanism • Energy stored in hydrogen ion gradient across membrane • Makes ATP from ADP
ATP Synthase • Enzyme helps make ATP • Located in membrane • Changes ADP to ATP • Uses energy from a proton gradient across membrane
The Reactions---Cell respire • Glycolysis • Krebs cycle (citric acid cycle) • Electron transport chain (oxidative phosphorylation)
Glycolysis • Happens in cytoplasm • Starts with glucose • Yields 2 pyruvate (3 carbons) molecules, 4 ATP (net of 2 ATP) & 2 NADH • 10 enzyme catalyzed reactions to complete
Glycolysis • Part one (priming) • First 5 reactions are endergonic • 2 ATP molecules attach 2 phosphate groups to the glucose • Produces a 6 carbon molecule with 2 high energy phosphates attached
Glycolysis • Part two (cleavage reactions) • 6 carbon molecule is split into 2 • 3-carbon molecules each with a phosphate (G3P)
Glycolysis • Part three (energy harvesting reactions) • In two reactions 2- G3P molecules are changed to pyruvate • 4 ATP molecules are made (net of 2) • An energy rich hydrogen is harvested as NADH (2NADH)
Glycolysis • Every living organism can carry out glycolysis • Occur in aerobic & anaerobic • Does not require oxygen • Oxygen present the Krebs cycle will begin
Glucose ATP 1 Hexokinase ADP Fig. 9-9-1 Glucose Glucose-6-phosphate ATP 1 Hexokinase ADP Glucose-6-phosphate
Glucose ATP 1 Hexokinase ADP Fig. 9-9-2 Glucose-6-phosphate Glucose-6-phosphate 2 Phosphoglucoisomerase 2 Phosphogluco- isomerase Fructose-6-phosphate Fructose-6-phosphate
Glucose ATP 1 1 Hexokinase ADP Fig. 9-9-3 Fructose-6-phosphate Glucose-6-phosphate 2 2 Phosphoglucoisomerase ATP 3 Phosphofructo- kinase Fructose-6-phosphate ATP ADP 3 3 Phosphofructokinase ADP Fructose- 1, 6-bisphosphate Fructose- 1, 6-bisphosphate
Glucose ATP 1 Hexokinase ADP Fig. 9-9-4 Glucose-6-phosphate 2 Phosphoglucoisomerase Fructose- 1, 6-bisphosphate 4 Fructose-6-phosphate Aldolase ATP 3 Phosphofructokinase ADP 5 Isomerase Fructose- 1, 6-bisphosphate 4 Aldolase 5 Isomerase Glyceraldehyde- 3-phosphate Dihydroxyacetone phosphate Glyceraldehyde- 3-phosphate Dihydroxyacetone phosphate
2 NAD+ 6 Triose phosphate dehydrogenase 2 P 2 NADH i + 2 H+ 2 2 1, 3-Bisphosphoglycerate Glyceraldehyde- 3-phosphate Fig. 9-9-5 2 NAD+ 6 Triose phosphate dehydrogenase P 2 2 NADH i + 2 H+ 2 1, 3-Bisphosphoglycerate
2 NAD+ 6 Triose phosphate dehydrogenase 2 P 2 NADH i + 2 H+ 2 1, 3-Bisphosphoglycerate 2 ADP 7 Phosphoglycerokinase Fig. 9-9-6 2 ATP 2 1, 3-Bisphosphoglycerate 2 ADP 2 3-Phosphoglycerate 7 Phosphoglycero- kinase 2 ATP 2 3-Phosphoglycerate
2 NAD+ 6 Triose phosphate dehydrogenase 2 P 2 NADH i + 2 H+ 2 1, 3-Bisphosphoglycerate 2 ADP 7 Phosphoglycerokinase Fig. 9-9-7 2 ATP 2 3-Phosphoglycerate 2 3-Phosphoglycerate 8 Phosphoglyceromutase 8 Phosphoglycero- mutase 2 2-Phosphoglycerate 2 2-Phosphoglycerate
2 NAD+ 6 Triose phosphate dehydrogenase 2 P 2 NADH i + 2 H+ 2 1, 3-Bisphosphoglycerate 2 ADP 7 Phosphoglycerokinase Fig. 9-9-8 2 ATP 2 2-Phosphoglycerate 2 3-Phosphoglycerate 8 Phosphoglyceromutase 9 Enolase 2 H2O 2 2-Phosphoglycerate 9 Enolase 2 H2O 2 Phosphoenolpyruvate 2 Phosphoenolpyruvate
2 NAD+ 6 Triose phosphate dehydrogenase P 2 2 NADH i + 2 H+ 2 1, 3-Bisphosphoglycerate 2 ADP 7 Phosphoglycerokinase Fig. 9-9-9 2 ATP Phosphoenolpyruvate 2 2 ADP 2 3-Phosphoglycerate 8 10 Phosphoglyceromutase Pyruvate kinase 2 ATP 2 2-Phosphoglycerate 9 Enolase 2 H2O 2 Phosphoenolpyruvate 2 ADP 10 Pyruvate kinase 2 ATP Pyruvate 2 2 Pyruvate
Oxidation of pyruvate • Pyruvate is changed into acetyl-CoA • First carboxyl group is removed • Leaves as carbon dioxide • 2 carbon molecule called acetate remains
Oxidation of pyruvate • Pyruvate dehydrogenase • Multienzyme complex • Combines acetate (acetyl group) with a coenzyme called coenzyme A. • Product is acetyl-CoA • Plus one NADH
Oxidation of pyruvate • Pyruvate dehydrogenase • Largest known enzyme • 60 subunits • Process occurs within mitochondria • Acetyl-CoA is end product of the break down of fats and proteins too
CYTOSOL MITOCHONDRION Fig. 9-10 NAD+ NADH + H+ 2 1 3 Acetyl CoA Coenzyme A Pyruvate CO2 Transport protein