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Lecture 7

BISC 101 - Lecture 7 - Cellular Respiration .docx

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Department
Biological Sciences
Course
BISC 101
Professor
Christopher Kennedy
Semester
Winter

Description
Biological Science 101 – General Biology Lecture Seven: Cellular Respiration Ch. 9, Pgs. 163-181 Figs. 9.2-9.20 Cellular Respiration: - A series of processes that is involved in converting food to energy (ATP) - Breakdowns food (Catabolism) - Aerobic process (O2) - Involves enzymes. - Conversion of food to energy One glucose molecule -> 38 Molecules of ATP Three Phases: 1) Glycolysis (sugar splitting) – Takes place in the cytoplasm. Glucose (6-C) -> -> -> (10 Steps) -> Pyruvate + (3-C) 2H2O 2) Citric Acid Cycle Pyruvate (3-C) -> Acetyl CO-A (2-C) -> -> -> (8 Steps) -> CO2 3) Electron transport (Oxidative Phosphorylation) - ATP is produced. - Energy Input:  2ATP -> 2ADP (Endergonic) - Energy Output:  4ATP (Exergonic)  2NADH  2 Pyruvate - Net Output:  2ATP (Energy Molecule)  2NADH (Energy Molecule)  2 Pyruvate Citric Acid cycle - Energy Output:  3NAD -> 3NADH (x2 for Pyruvate [2X])  1FAD -> 1 FADH (x2 for Pyruvate [2X])  1 ADP -> 1 ATP (x2 for Pyruvate [2X]) Electron transport chain Electron Transport: - Mitochondria inner membrane (cristae). - Electrons transferred step-by-step from NADH, FADH -> O2 (acceptor) Electron Loss -> Oxidized Electron Accept -> Reduced Chemiosmosis - Energy in the form of electrons is converted into ATP. - Enzyme involved is called ATP-Synthase. - Hydrogen ions (H+) accumulate outside the membrane, causing a differential charge is created (Proton-Motive-Force) Proton-Motive-Force -> Drives the ATP-Synthase Net yield of energy (ATP) Energy Production: Food -> Source of -> Glycolysis: -> Electrons -> Electron (Glucose) Electrons (2 ATP, 2 NADH) Transport Acetyl CoA: (2 NADH) Citric Acid: (6NADH, 2 FADH, 2 ATP) 10 NADH = 3 ATP 2 FADH = 2 ATP 4 ATP 30 ATP + 4 ATP + 4 ATP = 39 ATP (+/- 10%) Efficiency: 1 Glucose -> 686 kcal/mole 1 ATP -> 7.3 kcal/mole Efficiency in Respiration: 7.3 x 38 ATP = 686 kcal (40% Efficiency, 60% lost “as heat”) E.g. Car -> Gasoline -> 25% Efficiency. * Background Reading: Laboratory Week 4 Handout. Review Questions: 1. What is the role of ATP in the cell? Why is it considered a "high-energy" molecule? Energy captured -> ATP (Adenosine triphosphate) ATP drives transport and mechanical work. - ATP hydrolyses causes changes in shapes and binding affinities of proteins - ATP transports chemical energy within cells for metabolism. - It is produced by photophosphorylation and cellular respiration and used by enzymes and structural proteins in many cellular processes, including biosynthetic reactions, motility, and cell division. It is considered to be a “high-energy” molecule because it aids in intracellular energy transfer. 2. What does NAD+ do in the cell? + Another energy molecule: NAD (Nicotinamide Adenine Dinucleotide) NAD aids Oxidation -- Electrons --> Reduction - “High-energy foods”  Fats  Carbohydrates 3. What is an enzyme? What does it do in the cell? Enzymes: - Involved in catabolism. - Food broken down. - Energy released. - Catalytic proteins that speed up the rate of a reaction, without altering the end products or change the reaction. For chemical reactions to start, they requ
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