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Getting Energy to Make ATP

Getting Energy to Make ATP. Section 9.3. PG. 231. Why are mitochondria important?. Mitochondria use the energy by performing cellular respiration. All cells require energy in the form of _______. ATP.

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Getting Energy to Make ATP

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  1. Getting Energy to Make ATP Section 9.3 PG. 231

  2. Why are mitochondria important? Mitochondria use the energy by performing cellular respiration • All cells require energy in the form of _______. ATP • Cellular Respiration releases energy by breaking down food molecules in the presence of oxygen • Taking energy from food (glucose) and turning it into a form cells can use (ATP).

  3. Cell Respiration Equation 6O2 + C6H12O6 6CO2 + 6H2O + Energy Oxygen + Glucose  Carbon Dioxide + Water + Energy Does this equation look familiar? It is the reverse of photosynthesis!

  4. The Parts… • Cell Resp. is broken into three parts: • Glycolysis • Krebs Cycle • Electron Transport Chain • Each stage uses chemical energy to make ATP.

  5. GLYCOLYSIS (Step 1) • One molecule of glucose is broken in half, producing two 3-carbon molecules called pyruvic acid (pyruvate). • Occurs in ______________. Cytoplasm

  6. Advantages Fast Doesn’t require oxygen Disadvantages Cell’s NAD+ gets used up so quickly, glycolysis can’t go on for long Glycolysis

  7. After Glycolysis… Two Options: Fermentation & Glycolysis Alcoholic Fermentation Fermentation No oxygen present Lactic Acid Fermentation Glycolysis (Respiration) Electron Transport Chain Oxygen present Krebs Cycle Fermentation = No ATP Respiration = Lots of ATP

  8. The rest of Cell Respiration • If oxygen is present, the cell performs cellular respiration • 90% of the energy from glucose is still unused • Final two steps in cell respiration extract that energy using oxygen. • Aerobic processes

  9. CITRIC ACID CYCLE (Step 2) • A.K.A Krebs Cycle • During the Krebs cycle, pyruvate is broken down into CO2 + energy • The Krebs cycle takes place in the matrix of the mitochondria. Matrix

  10. Krebs Cycle • Pyruvicacid enters the mitochondrial matrix • One carbon molecule is lost as CO2 while NAD+  NADH • Remaining two carbon molecules combine with coenzyme A to form Acetyl-CoA.

  11. Krebs Cycle • Acetyl-CoA adds the 2-carbon group to a 4-carbon group to make citric acid. • Citric acid is broken down into a 4-carbon molecule and two CO2 molecules are released • During this process, energy is released in the form of NADH, FADH2, and ATP • The remaining 4-carbon molecule, oxaloacetic acid (OAA), is used to restart the cycle.

  12. Krebs Cycle (pg. 233)

  13. ELECTRON TRANSPORT CHAIN (Step 3) • What was the ETC used for in photosynthesis? • The electron transport chain uses high-energy electrons from the Krebs cycle to make ATP • Occurs in ____________________. Cristae (inner membrane)

  14. Electron Transport Chain • Electrons from NADH and FADH2 are transported to the ETC • lies in the membrane of the mitochondrion • Oxygen is very electronegative (it draws electrons near it) - this causes the electrons to move down the ETC towards oxygen • Oxygen is the final electron acceptor • At the end of the chain, a protein enzyme combines the electrons with H+ and O- to make H2O

  15. Electron Transport Chain • Every time 2 electrons move down the ETC, their energy pumps H+ ions into the inner membrane space, creating a concentration gradient • The H+ ions then move through ATP synthase molecules, and each time it rotates, it creates ATP • Each pair of electrons yields 3 ATP molecules

  16. Cell Respiration Table

  17. The Totals Glycolysis 2 ATP Krebs Cycle & Electron Transport 34 ATP _______ Total 36 ATP

  18. FERMENTATION • When no oxygen is present, glycolysis is followed by fermentation rather than the Krebs cycle • Fermentation releases energy from food in the absence of oxygen.

  19. Converts NADH to NAD+ • Frees up NAD+ so glycolysis can continue and make more ATP • Is anaerobic • Does not require oxygen

  20. Types of Fermentation • Alcoholic Fermentation (yeast & bacteria) • Used to make cheese, bread, wine, buttermilk, yogurt, etc.. Pyruvate + NADH  alcohol + CO2 + NAD+ Lactic Acid Fermentation(muscle cells, yogurt, sauerkraut) • Build up of lactic acid makes muscles sore pyruvate + NADH  lactic acid + NAD+ New theory: Hydrogen ions released from ATP (C10H16N5O13P3 ) cause low pH in the blood=acidosis

  21. Cellular Respiration vs. Fermentation Comparison of Fermentation to Cellular Respiration Lactic Acid Alcoholic Cellular respiration glucose glucose glucose glycolysis (pyruvic acid) glycolysis (pyruvic acid) glycolysis (pyruvic acid) carbon dioxide carbon dioxide lactic acid water alcohol 2 ATP 2 ATP 36 ATP

  22. COMPARING PHOTOSYNTHESIS AND CELLULAR RESPIRATION Both use: • eˉ carriers and chemical reactions to make ATP • ETC to form ATP by creating and using a proton (H+) gradient with ATP Synthase to “crank out” ATP Photosynthesis: • Produces high energy sugars and O2 using sunlight and CO2 & H2O Cellular Respiration: • Uses high energy sugars and O2 without sunlight to produce CO2 & H2O

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