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 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

C 6 H 12 O O 2 ---> 6 CO H 2 O + 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

NAD & NADH

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 Free energy, G Controlled release of energy for synthesis of ATP 2 H e – 2 H + 1 / 2 O 2 (from food via NADH) ATP 1 / 2 O 2 2 H + 2 e – Electron transport chain H2OH2O

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)

Cellular respiration

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

Fig ATP ADP Hexokinase 1 ATP ADP Hexokinase 1 Glucose Glucose-6-phosphate Glucose Glucose-6-phosphate

Fig Hexokinase ATP ADP 1 Phosphoglucoisomerase 2 Phosphogluco- isomerase 2 Glucose Glucose-6-phosphate Fructose-6-phosphate Glucose-6-phosphate Fructose-6-phosphate

1 Fig Hexokinase ATP ADP Phosphoglucoisomerase Phosphofructokinase ATP ADP 2 3 ATP ADP Phosphofructo- kinase Fructose- 1, 6-bisphosphate Glucose Glucose-6-phosphate Fructose-6-phosphate Fructose- 1, 6-bisphosphate Fructose-6-phosphate 3

Fig Glucose ATP ADP Hexokinase Glucose-6-phosphate Phosphoglucoisomerase Fructose-6-phosphate ATP ADP Phosphofructokinase Fructose- 1, 6-bisphosphate Aldolase Isomerase Dihydroxyacetone phosphate Glyceraldehyde- 3-phosphate Aldolase Isomerase Fructose- 1, 6-bisphosphate Dihydroxyacetone phosphate Glyceraldehyde- 3-phosphate 4 5

Fig NAD + NADH H + 2 2P i Triose phosphate dehydrogenase 1, 3-Bisphosphoglycerate 6 2 NAD + Glyceraldehyde- 3-phosphate Triose phosphate dehydrogenase NADH2 + 2 H + 2 P i 1, 3-Bisphosphoglycerate 6 2 2

Fig NAD + NADH 2 Triose phosphate dehydrogenase + 2 H + 2 P i 2 2 ADP 1, 3-Bisphosphoglycerate Phosphoglycerokinase 2 ATP 2 3-Phosphoglycerate ADP 2 ATP 1, 3-Bisphosphoglycerate 3-Phosphoglycerate Phosphoglycero- kinase 2 7

Fig Phosphoglycerate Triose phosphate dehydrogenase 2 NAD + 2 NADH + 2 H + 2 P i 2 2 ADP Phosphoglycerokinase 1, 3-Bisphosphoglycerate 2 ATP 3-Phosphoglycerate 2 Phosphoglyceromutase 2-Phosphoglycerate Phosphoglycero- mutase

Fig NAD + NADH H + Triose phosphate dehydrogenase 2 P i 1, 3-Bisphosphoglycerate Phosphoglycerokinase 2 ADP 2 ATP 3-Phosphoglycerate Phosphoglyceromutase Enolase 2-Phosphoglycerate 2 H 2 O Phosphoenolpyruvate Phosphoglycerate Enolase 2 2 H 2 O Phosphoenolpyruvate 9

Fig Triose phosphate dehydrogenase 2 NAD + NADH ADP 2 ATP Pyruvate Pyruvate kinase Phosphoenolpyruvate Enolase 2 H 2 O 2-Phosphoglycerate Phosphoglyceromutase 3-Phosphoglycerate Phosphoglycerokinase 2 ATP 2 ADP 1, 3-Bisphosphoglycerate + 2 H ADP 2 ATP Phosphoenolpyruvate Pyruvate kinase 2 Pyruvate 10 2 P i

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

Fig CYTOSOLMITOCHONDRION NAD + NADH+ H Pyruvate Transport protein CO 2 Coenzyme A Acetyl CoA