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Unraveling the Mysteries of Cellular Respiration

Learn about Cellular Respiration, Glycolysis, Krebs Cycle, ATP, and the Laws of Thermodynamics in this comprehensive guide. Understand how energy is harnessed from glucose breakdown in the presence of oxygen and navigate through the intricate process step by step.

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Unraveling the Mysteries of 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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