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Cellular Respiration and Fermentation

Cellular Respiration and Fermentation. Lab Topic 5. Both Cellular respiration and fermentation are processes that transfer the energy in glucose bonds to the bonds in ATP (adenosine triphosphate) The energy in ATP is then used to perform cellular work

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Cellular Respiration and Fermentation

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  1. Cellular Respiration and Fermentation Lab Topic 5

  2. Both Cellular respiration and fermentation are processes that transfer the energy in glucose bonds to the bonds in ATP (adenosine triphosphate) • The energy in ATP is then used to perform cellular work • All living organisms produce ATP by either respiration or fermentation • Both processes involve a series of oxidation-reduction reactions (redox) where 1 reactant will be oxidized (loses electrons) and 1 will be reduced (gains electrons) Cellular Respiration & Fermentation

  3. Cellular Respiration is the aerobic process (requires oxygen) • C6H12O6 + 6 O2 --------------> 6 H2O + 6 CO2 + ATP • Glucose is oxidized and a coenzyme called nicotinamide adenine dinucleotide (NAD+) accepts the H atoms and is reduced • NADH then transfers electrons to the electron transport chain where it is passed down through a series of redox reactions and the energy released is used to phosphorylate a molecule of ADP creating ATP Cellular Respiration & Fermentation

  4. Cellular respiration actually occurs in 3 metabolic stages: • Glycolysis- • Occurs in the cytoplasm of the cell • Begins the breakdown of glucose into 2 molecules of pyruvic acid • Krebs cycle • Occurs in the mitochondria • Completes the breakdown of glucose to CO2 • Small amounts of ATP are produced during these stages Cellular Respiration & Fermentation

  5. ETS • Occurs in the mitochondria • Electrons from hydrogen carriers NAD+ and FADH+ (flaven adenine dinucleotide) • Chain uses the down hill flow of electrons from NADH and FADH to oxygen to pump H+ ions across the membrane • ATP synthase will make most of the cells ATP by chemiosmosis Cellular Respiration & Fermentation

  6. Fermentation is the anaerobic process-occurs when there is no oxygen present • Involves Glycolysis but does not involve the Krebs cycle or the ETS • There are 2 types: • Alcoholic Fermentation-Plants and some fungi convert pyruvate to ethanol and CO2 • Lactic Acid Fermentation-Animals, fungi, and some bacteria convert pyruvate to lactate Cellular Respiration & Fermentation

  7. Cellular Respiration is much more efficient than fermentation in producing ATP • Cellular Respiration can produce up to 38 ATP molecules and fermentation only produces 2 ATP Cellular Respiration & Fermentation

  8. Procedures • Read Pages 111-112 and answer the questions on page 113-114 • Half the class will be doing 5.1 A: Alcoholic Fermentation • Other half of the class will be doing 5.2 A: Cellular Respiration • Everyone is responsible for understanding both experiments Cellular Respiration & Fermentation

  9. Alcoholic Fermentation in Yeast Cells • We will be looking at alcoholic fermentation in yeast which is a single-celled fungus • When oxygen is low yeast will switch from cellular respiration to alcoholic fermentation • We will be measuring the CO2 that is released using a respirometer • You will be looking at the rate of fermentation as is it is affected by the concentration of yeast Cellular Respiration & Fermentation

  10. Before you begin write down your hypothesis and prediction on page 116 • Follow the instructions exactly as outlined on pages 116-117 • Complete table 5.2 • Answer questions on page 118-119 and compose your graph Cellular Respiration & Fermentation

  11. Cellular Respiration • We will be looking at cellular respiration in isolated mitochondria from pulverized lima beans and sucrose which will be source of glucose • Study the rate of cellular respiration by looking at 1 step in the Krebs cycle which converts Succinate to Fumarate • Succinate loses hydrogen ions (oxidized) and a coenzyme FAD is reduced Cellular Respiration & Fermentation

  12. We will use a substance called DPIP which is an electron acceptor that changes color • DPIP is blue in the oxidized state and colorless in the reduced state • We will use this color change to measure the respiration rate • We will use an instrument that is called a spectrophotometer to measure the amount of light absorbed by a pigment • As the DPIP changes from blue to clear it will absorb less light so more light will be transmitted • As more light passes through you should expect the transmittance readings to go up Cellular Respiration & Fermentation

  13. You will be looking at the effect of changing the amount of succinate (our substrate) on the cellular respiration rate • Before you begin write down your hypothesis and prediction on pages 122-123 • Follow the instructions exactly on pages 123-124 • Complete table 5.4 • Answer questions on page 125-126 and compose your graph Cellular Respiration & Fermentation

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