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Cellular Respiration

Cellular Respiration. I. Laws of Thermodynamics. A. Energy can never be created or destroyed . The sum of energy in the universe is constant. 1. 1 st law of thermodynamics – cells cannot take energy out of thin air it must harvest it somewhere

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Cellular Respiration

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  1. Cellular Respiration

  2. I. Laws of Thermodynamics • A. Energy can never be created or destroyed. The sum of energy in the universe is constant. • 1. 1st law of thermodynamics – cells cannot take energy out of thin air it must harvest it somewhere • 2. 2nd law of thermodynamics – energy transfer leads to less organization or increase in entropy

  3. II. Chemical Energy & Food • A. One gram of sugar can release 3811 calories of heat (1 kilocalorie found on food labels is 1000 calories) • B. Cells do not “burn” glucose, instead, they gradually release energy by breaking down the molecular bonds

  4. III. Cellular Respiration • A. Cellular Respiration is the process that releases energy by breaking down glucose and other food molecules in the presence of oxygen. 6O2 + C6H12O6  6CO2 + 6H2O + Energy Oxygen + Glucose  Carbon dioxide + Water + Energy • B. Cellular Respiration does not release the energy at once instead it occurs in steps releasing energy little by little

  5. III. Cellular Respiration • C. Steps of Cellular Respiration: • 1. Glycolysis (substrate phosphorylation) • Formation of acetyl CoA • 2. Krebs Cycle • 3. Oxidative phosphorylation/Electron Transport Chain (ETC) • D. Each step captures some of the chemical energy available in food molecules and uses it to produce ATP. What is ATP?????

  6. IV. ATP • A. Adenosine triphosphate (ATP) – is a molecule of adenosine bonded to three phosphates. • 1. An enormous amount of energy is packed in between the phosphate bonds, specifically the 3rd one. ATP  ADP + Pi + energy

  7. Steps of Cellular Respiration • 1. Glycolysis (substrate phosphorylation) • Formation of acetyl CoA • 2. Krebs Cycle • 3. Oxidative phosphorylation/Electron Transport Chain (ETC)

  8. V. Glycolysis • A. Glycolysis is the process in which one molecule of glucose is broken in half, producing 2 molecules of pyruvic acid, a 3-carbon compound. • B. Glycolysis releases energy(4) but needs a little bit of energy(2) to begin the process. • C. During glycolysis 4 high-energy electrons are removed and carried by NAD+ converting it into 4 NADH

  9. Formula for glycolysis (glucose breaking) Occurs in the cytoplasm Glucose + 2ATP+2NAD+2Pyruvic acid+4ATP+ 2NADH Several small Enzyme rxn.s

  10. VI. Glycolysis Without Oxygen • A. If oxygen is not present during glycolysis it follows a slightly different path known as fermentation. • B. Because fermentation does not require oxygen it is said to be anaerobic. There are 2 types of fermentation • 1. Alcoholic fermentation • 2. Acid fermentation

  11. VI. Glycolysis Without Oxygen • a. Yeast and other microorganisms use alcoholic fermentation, transforming pyruvic acid into ethyl alcohol and carbon dioxide waste • b. Lactic acid is produced during rapid exercise when your muscles aren’t supplied with plenty of oxygen. (muscle cramps)

  12. VII. Where are we in the cell? • Structure of a mitochondria

  13. IIX. Formation of Acetyl CoA • A. When oxygen is present pyruvic acid is transported to the mitochondion. • B. Each pyruvic acid (3-carbon molecule) is converted into acetyl coenzyme A (2-carbon molecule) and CO2 is released. Equation: 2 Pyruvic acid + 2 Coenzyme A + 2 NAD+ 2 Acetyl CoA + 2 CO2 + 2 NADH

  14. IX. Krebs Cycle (Citric acid) • A. In order for the Krebs cycle to follow glycolysis you need oxygen to be present this process is said to beaerobic. (cellular respiration) • B. During Krebs cycle acetyl coenzymes are broken down into carbon dioxide in a series of energy-extracting reactions in the mitochondria matrix. • 1. During the Krebs cycle oxaloacetate combines with acetyl CoA to create citric acid (6-carbon molecule) • 2. The electron carriers accepting the e- (NAD+ & FAD)will generate huge amounts of ATP

  15. 2 pyruvic acid + 8NAD+ + 2FAD + 2ADP 6CO2 + 8NADH + 2FADH2 + 2ATP

  16. X. Electron Transport “Pay off” • A. ETC uses the high-energy electrons to convert ADP to ATP • 1. e- come from NADH and FADH2 • B. The electron transport chain is located along the mitochondria inner membrane (cristae) • C. Oxygen is the final accepter of these high-energy electrons, creating water (waste product) at the end of the reactions. This is called oxidative phosphorylation

  17. All together we created 12 high energy carries 2 NADH glycolysis, 2NADH Acetyl CoA, 6 NADH Krebs, 2 FADH2 Krebs

  18. X. Electron Transport “Pay off” • D. NADH & FADH2 shuttle electrons to the ETC and the hydrogen atoms are split. H2 2H+ + 2e- • E. The e- are passed down protein carries (cytochromes); while the hydrogen ions are pumped using some the energy across the inner membrane into the intermembrane space creating a pH gradient/proton gradient. • H ions only diffuse back through ATP synthase

  19. XI. The Totals • Glycolysis: ____ • Krebs Cycle: ___ • ETC:____ For every 1 NADH 3 ATP made For every 1 FADH2 2 ATP made

  20. Photosynthesis vs. Cellular Respiration Function Location (organelle) Reactants Products Equation

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