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Cellular Energetics Review

Cellular Energetics Review. Chapters 9 & 10. Cellular respiration. Catabolic, energy-yielding pathway Glucose + oxygen → carbon dioxide + water Energy released is ATP and heat Glycolysis Kreb’s/Citric Acid Cycle Electron Transport Chain and oxidative phosphorylation. Glycolysis.

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Cellular Energetics Review

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  1. Cellular Energetics Review Chapters 9 & 10

  2. Cellular respiration • Catabolic, energy-yielding pathway • Glucose + oxygen → carbon dioxide + water • Energy released is ATP and heat • Glycolysis • Kreb’s/Citric Acid Cycle • Electron Transport Chain and oxidative phosphorylation

  3. Glycolysis • “splitting of sugar” glucose into 2 pyruvate • Occurs in cytoplasm • Net result: use 2 ATP, make 4 ATP, 2 pyruvates, and 2 NADH • NAD+ gets reduced (electrons added) to make NADH • Carries electrons to transport chain

  4. Middle Step • Pyruvate enters mitochondria • Enzyme chops off a carbon dioxide, transfers an electron to make NADH, and creates acetyl CoA • 2 pyruvates makes 2 of each of the above

  5. Kreb’s Cycle • Acetyl CoA enters cycle • For every one, you get 3 NADH, 1 FADH2, 2 carbon dioxides, 1 ATP • 2 acetyl CoA makes double of above

  6. Electron Transport Chain • The 10 NADH and 2 FADH2 carry electrons to a chain of membrane bound enzymes • The electrons move down the chain • A gradient of hydrogen ions begins to build • Oxygen is the final electron acceptor… water is made

  7. Oxidative Phosphorylation • Build up of H+ goes through ATP synthase • ATP synthase spins… uses kinetic energy to assemble ATP from ADP and P • Typically each NADH will make 3 ATP and each FADH2 will make 2 ATP for a maximum of 34 ATP

  8. Fermentation • Cellular respiration requires oxygen • Fermentation does not • In absence of oxygen, glycolysis occurs • You get 2ATP, 2 pyruvate and 2 NADH • Fermentation takes the pyruvate and NADH and converts them to waste and NAD+ • This allows for more glycolysis • Wastes: alcohol (plants) lactic acid (animals)

  9. Food and Energy • Proteins, carbohydrates, and fats can all be converted to molecules that can enter the cellular respiration pathway • They can all be broken down and used to make ATP!

  10. Photosynthesis • Carbon dioxide + water → glucose + oxygen • Light dependent reactions • Light independent reactions • Chloroplasts and chlorophyll

  11. Photolysis/Light Reactions • The energy of light splits water into oxygen and electrons • NADP+ becomes reduced to NADPH • Chemiosmosis uses H+ gradient to make ATP • Cyclic electron flow: generates extra ATP for Calvin cycle • Noncyclic electron flow: only makes NADPH

  12. Dark Reactions/Calvin Cycle • Uses ATP and NADPH created in light reactions to perform carbon fixation (turning carbon dioxide into sugars) • Rubisco is main enzyme; it joins carbon dioxide to RuBP (5 carbon sugar) • Every turn of Calvin cycle uses 3 carbon dioxides and nets one 3 carbon sugar and regenerates RuBP for the next turn

  13. C4/CAM Photosynthesis • C4: when stomata are closed, oxygen can build up and compete with carbon dioxide for Rubisco (photorespiration) • C4: PEP carboxylase has higher affinity for carbon dioxide (mesophyll cell collects carbon dioxide and funnels into bundle sheath cell for Calvin cycle • CAM: open stomata only at night, carbon fixation occurs at night, and calvin cycle in day

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