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1. ATP serves as a common energy source for organisms because

D.N.A Objective: Sequence the events of cell respiration, including major reactants and products of glycolysis, krebs cycle, ETC, and fermentation. 1. ATP serves as a common energy source for organisms because A. it is the smallest energy molecule

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1. ATP serves as a common energy source for organisms because

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  1. D.N.AObjective: Sequence the events of cell respiration, including major reactants and products of glycolysis, krebs cycle, ETC, and fermentation. 1. ATP serves as a common energy source for organisms because A. it is the smallest energy molecule B. it stores the least energy of any energy source C. its energy can be easily transferred to do cellular work D. it is extremely stable and can be stored in the cell for long periods of time E. traces of it have been found in fossils of ancient organisms dating back to the beginning of life on Earth 2. Which metabolic process is common to both aerobic cellular respiration and alcoholic fermentation? • Krebs cycle • Glycolysis • Electron transport chain • Conversion of pyruvic acid to acetyl CoA • Production of a proton gradient

  2. D.N.AObjective: Sequence the events of cell respiration, including major reactants and products of glycolysis, krebs cycle, ETC, and fermentation. • Which of the following describes glycolysis? A. It begins the oxidation of glucose B. It produces a small amount of ATP C. Generates NADH • Splits glucose to form two molecules of pyruvate • All of the above • What is the function of O2 in aerobic metabolism A. Oxidizes glucose, making it more soluble in water B. Reduces enzymes, limiting glucose synthesis C. Activates enzymes in the citric acid (Krebs) Cycle D. Accepts electrons through the electron transport chain E. Transforms ion gates to allow diffusion of K+

  3. During complete aerobic cellular respiration, each molecule of glucose broken down in the mitochondria can yield 36 molecules of ATP. What conditions might lead to a decrease in the amount of ATP produced in a given system? A. An increase in the amount of glucose added to the system B. A decrease in the amount of light the system is exposed to C. A decrease in the amount of oxygen available in the system D. A decrease in the amount of carbon dioxide available in the system E. An increase in the amount of ADP in the system

  4. Cellular Respiration Overview

  5. Cellular Respiration • Aerobic Cellular Respiration occurs in the presence of oxygen in the cytosol and the mitochondria • The process can be summarized as: C6H12O6 + 6O2 6CO2 + 6H2O + Energy (ATP and Heat) Organic Compounds Oxygen Water Energy + CO2 + +

  6. Redox Reaction • Redox Reactions – Reactions involving the transfer of electrons • Oxidation – When a substance loses electrons in a redox reaction • The substance accepting the electron is known as the oxidizing agent • Reduction – When a substance gains electrons in a redox reaction • The substance donating the electron is known as the reducing agent

  7. Example: Sodium Chloride Becomes Oxidized (loses electron) Oxidizing Agent + - Na Cl Na Cl + + Reducing Agent Becomes Reduced (gains electron)

  8. Production of ATP Becomes Oxidized Oxidizing Agent 6H2O C6H12O6 6O2 6CO2 Energy + + + Reducing Agent Becomes Reduced

  9. Overview of the Process • With oxygen present, there are 3 main steps in cellular respiration: • Glycolysis • The Citric Acid Cycle (Krebs Cycle) • Oxidative Phosphorylation: ETC and chemiosmosis

  10. NADH NADH and FADH2 Oxidative Phosphorylation: ETC And Chemiosmosis Citric Acid Cycle Glycolysis Glucose Pyruvate ATP ATP ATP

  11. Types of Phosphorylation • Phosphorylation is how ATPs are formed • Oxidative Phosphorylation – Phosphates added to ADP via the redox reactions in the ETC • Substrate Level Phosphorylation – An enzyme transfers a phosphate from a substrate, to ADP (glycolysis and citric acid cycle)

  12. Glycolysis • Glyco=Sugar; Lysis= Split • InGlycolysis, Glucose is split into two 3-carbon pyruvate (pyruvic acid) molecules • In order to begin, glycolysis requires the input of energy (ATP) • Glycolysis occurs in the cytosol • Lets look at Glycolysis in a very simple form:

  13. Net Gain in Glycolysis • 2 ATP - 2 ATP (Energy investment phase) + 4 ATP (Energy yielding phase) + 2 ATP • 2 NADH • Electron carriers • Will be used to make ATP later  • 2 Pyruvate

  14. 2ATP 4 ADP Glucose 4ATP C C C C C C 2 NADH Pyruvic Acid C C C C C C 2 ADP C C C C C C 2 NAD+

  15. Citric Acid Cycle • Also referred to as the Krebs Cycle • Takes place in the mitochondrial matrix • When oxygen is present, the Citric Acid Cycle follows Glycolysis • This cycle takes pyruvate from glycolysis to make ATP, NADH, and FADH2

  16. Citric Acid Cycle Simplified • Pyruvate turns into acetyl CoA • Acetyl CoA enters the Citric Acid Cycle and is then transformed into citrate

  17. Citric Acid Cycle - Products • 3 NADH, 1 FADH2, 1ATP, and CO2 are produced in the Citric Acid Cycle • Each NADH will generate about 3 ATP • FADH2 will generate about 2 ATP • The CO2 released from this cycle is the same CO2 that you exhale while breathing

  18. Electron Transport Chain • The ETC converts the NADH and FADH2 from glycolysis and the Krebs Cycle into ATP • Occurs in inner membrane of mitochondrion • The energy in each NADH molecule moves enough protons (H+) into the mitochondrial matrix to create ATP (oxidative phosphorylation)

  19. Oxidative Phosphorylation • This is the process of extracting ATP form the energy in NADH and FADH2 • Occurs in the cristae of the mitochondria • The electrons are passed through an ETC to release ATP • The final electron acceptor is oxygen • Oxygen bonds with 2 electrons (carried by Hydrogen) to produce water

  20. e- e- H H ADP ATP ADP ATP ADP ATP Energy Level ADP ATP O

  21. Chemiosmosis • The energy the electrons lose along the way moves H+ out of the matrix and into the intermembrane space of the mitochondrion • As H+ ions diffuse through the membrane, ATP synthase uses the energy to join ADP and a phosphate group  ATP

  22. Aerobic Respiration: Total Energy Yield • Glycolysis: • 2 ATP (Net) • 2 NADH  6 ATP • Krebs Cycle: • 2 ATP • 8 NADH  24 ATP (ETC) • 2 FADH2  4 ATP (ETC) • TOTAL: • 8 ATP + 30 ATP  38 ATP

  23. Anaerobic Environments • When no oxygen is present, the cell will have to do one of two things: • Die due to the fact that there is no Oxygen to accept electrons at the end of oxidative, so no more NAD+ are made or • They can undergo Fermentation: • Lactic Acid • Alcoholic

  24. Fermentation • Takes place in the mitochondrial inner membrane • Does not require oxygen to occur • Does not directly produce ATP

  25. Alcoholic Fermentation • Occurs in some BACTERIA and YEAST • 2 step process: • Carbon dioxide is released from pyruvate (3-C), forming acetaldehyde (2-C) • Acetaldehyde is reduced by NADH (gains an electron), forming ethyl alcohol (ethanol) • NAD+ is regenerated, thereby allowing glycolysis to continue • Used to produce beer and wine

  26. Lactic Acid Fermentation • Occurs in ANIMALS • 1 step process: • Pyruvate is reduced by NADH (gains an electron), forming lactic acid • NAD+ is regenerated, thereby allowing glycolysis to continue • Occurs in muscle cells, causing muscle pain and fatigue

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