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Lecture 7
Lecture 7
Lecture 7
Lecture 7
Lecture 7
Lecture 7
Lecture 7
Lecture 7
Lecture 7
Lecture 7
Lecture 7
Lecture 7
Lecture 7
Lecture 7
Lecture 7
Lecture 7
Lecture 7
Lecture 7
Lecture 7
Lecture 7
Lecture 7
Lecture 7
Lecture 7
Lecture 7
Lecture 7
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Lecture 7

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  • 1. Lecture 7: Harvesting Energy – Glycolysis & Cell Respiration COVERS CHAPTER 8
  • 2. How do we get energy from food? * • Glucose + O2 >> CO2 + H2O + ATP • We breathe O2 and eat food (glucose), and convert that to CO2, water and ATP (energy for our cells to function)
  • 3. The Big Picture* • Glycolysis and Cell Respiration are both part of a larger CYCLE of life: • Plants (and other autotrophs) take sunlight and water and CO2 and make glucose from it via photosynthesis. Oxygen is a byproduct of this reaction. • Humans (and other animals-heterotrophs) take the glucose in (by eating plant material and other foods) and break it down. Water and CO2 are by products. • In this way, plants give us what we need (O2 and glucose) and we supply the plants with water and CO2.
  • 4. Photosynthesis Provides the Energy Released by Glycolysis and Cellular Respiration Fig. 8-1 ATP H2O O2 CO2 C6H12O6 glycolysis photosynthesis energy from sunlight cellular respiration 66 6
  • 5. What do we use energy for?* • Most cellular energy in the body is stored in the chemical bonds of ATP • Cells require a continuous supply of energy to – Run chemical reactions – Grow – Reproduce – Move the body
  • 6. More big picture* • This lecture describes the reactions that move the energy from energy STORAGE molecules (like glucose and fat) to energy CARRYING molecules (like ATP, NADH and FADH2) • About 40% of the energy in glucose can be transferred to ATP, the rest is released as heat. • Cells break down glucose (the most common energy storage molecule) and give it to energy carrying molecules (ATP) via 2 separate reactions: – Glycolysis (2 steps) • Glucose activation • Energy Harvest – Cellular Respiration (3 steps) • Creation of Acetyl CoA • Krebs Cycle • Oxidative Phosphorylation
  • 7. A Summary of Glucose Breakdown Fig. 8-2 cellular respiration glucose glycolysis fermentation2 pyruvate lactate ethanol + CO2 (cytoplasmic fluid) mitochondrion ATP CO2 34 or 36 ATP2 6 H2O O2 6 6 If no O2 is availableIf O2 is available
  • 8. Glycolysis: 2 parts • Takes place in cytoplasm • Starts with a molecule of glucose, ends with PYRUVATE • Is an anaerobic reaction: can happen even in the absence of oxygen • 2 parts – Glucose activation: a glucose molecule is energized by the addition of TWO high energy phosphates FROM TWO ATP molecules, leaving ADP. (Yes, you have to spend ATP to make it!) – Energy Harvest: The products of these reactions give high energy phosphates back to 4 ADP molecules, resulting in the creation of 4 ATP molecules (but only a NET production of 2 ATPs.) Also, 2 high energy electrons and a hydrogen ion are added to “empty” electron carrier NAD+ to make NADH. Pyruvate is the end product of glycolysis.
  • 9. The Essentials of Glycolysis Fig. 8-3 glucose fructose bisphosphate G3P pyruvate NAD+ ADPATP 2 2 2 22 4 4 2 ADP NADH ATP Energy harvestGlucose activation CC CCCC CC CC C CC C CCCC PPP 1 2
  • 10. Glycolysis* • One molecule of glucose is transformed into 2 molecules of pyruvate • Pyruvate then moves into the mitochondrial matrix
  • 11. Anatomy of a mitochondrion* • Outer membrane: most small molecules can freely diffuse across • Intermembrane Space: space between inner and outer membrane • Inner Membrane: high ratio of proteins to lipids-most molecules must pass through protein channels • Cristae: internal compartments formed by the inner membrane • Matrix: space inside inner membrane
  • 12. Cell Respiration: Big Picture* • Pyruvate (from glycolysis) is broken down (for every molecule of glucose entering glycolysis, keep in mind TWO pyruvates are made.) • Energy is extracted (given to energy carrying molecules) • CO2 and H2O are released • Happens in mitochondria • 3 reactions make up cellular respiration: – Creation of Acetyl CoA (matrix) – Kreb’s Cycle (AKA TCA Cycle, Citric Acid Cycle) (matrix) – Oxidative Phosphorylation (across inner mito membrane from matrix to intermembrane space)
  • 13. Creation of Acetyl CoA & Kreb’s Cycle • Pyruvate >> Acetyl CoA (intermediate) + CO2 • Acetyl CoA >> H2O + 2 ATP + more CO2 + NADH + FADH2 + H ions • CO2 LEAVES THE MITOCHONDRIA • 2 ATP are made • **High energy electrons and hydrogen ions are transferred to energy carrying molecules NAD+ (10) and FAD (2), turning them into 10 NADH and 2 FADH2. **follow the NADH, FADH2 and H ions!
  • 14. Creation of Acetyl CoA
  • 15. Kreb’s Cycle
  • 16. Oxidative Phosphorylation • 4 high energy electrons are transferred from NADH and FADH2 to the ELECTRON TRANSPORT CHAIN, embedded in the inner mito membrane. • The electrons “jump” from molecule to molecule along the chain, losing small amounts of energy each time. SOME OF THIS ENERGY is used to pump H atoms across inner membrane and into intermembrane space. • Result is HIGH H+ concentration inside the intermembrane space. • Electrons reach the “end” of the transport chain and are transferred to oxygen. • H atoms and oxygen combine to form WATER.
  • 17. Oxidative Phsophorylation • FINALLY, H atoms flow DOWN their gradient from intermembrane space BACK to the matrix • ADP and free phosphate are waiting there, and they combine to form ATP. • ATP leaves matrix and mitochondria and enter cytoplasm to fuel cell’s processes. (and more ADP moves into matrix to make more ATP.
  • 18. Oxidative Phosphorylation
  • 19. Another pic of Oxidative Phosphorylation
  • 20. ATP Yield* • One molecule of glucose going through glycolysis can generate TWO molecules of ATP. If the material continues through cell respiration, another 34-36 molecules of ATP can be generated.
  • 21. Aerobic vs anaerobic reactions • Glycolysis is an anaerobic reaction: it can happen even in the absence of oxygen • Cellular Respiration requires oxygen to happen: it is an aerobic reaction. • (If there is no oxygen available, a cell cannot do cell respiration, and instead performs a fermentation reaction. Lactate-lactic acid- is a byproduct of fermentation.)
  • 22. Fig. 8-2 cellular respiration glucose glycolysis fermentation2 pyruvate lactate ethanol + CO2 (cytoplasmic fluid) mitochondrion ATP CO2 34 or 36 ATP2 6 H2O O2 6 6 If no O2 is availableIf O2 is available
  • 23. Can we get energy from other molecules besides glucose? • Keep in mind that most animals can harvest ATP from a number of different molecules (like glycogen-storage form of glucose- and fats and proteins), but glucose is the PRIMARY source of our ATP. • (We would have to break down these other molecules and they can enter the cell respiration pathway at different points.)
  • 24. Proteins and Fats can give us energy!

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