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Respiration

Respiration. Cells - energy to do work - stored as organic molecules - broken down to get energy. 2 ways - 1 in absence of oxygen (fermentation). Other aerobic (presence of oxygen) - respiration. http://www.jracademy.com/~vinjama/2003pics/fermentation%5B1%5D.jpg.

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Respiration

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  1. Respiration

  2. Cells - energy to do work - stored as organic molecules - broken down to get energy. • 2 ways - 1 in absence of oxygen (fermentation). • Other aerobic (presence of oxygen) - respiration.

  3. http://www.jracademy.com/~vinjama/2003pics/fermentation%5B1%5D.jpghttp://www.jracademy.com/~vinjama/2003pics/fermentation%5B1%5D.jpg

  4. Formula for respiration: C6H12O6 + 6O2 -> 6CO2 + 6H2O + Energy (ATP + heat) • Glucose traditionally used - any organic molecule can be starting material.

  5. http://tidepool.st.usm.edu/pix/resp.gif

  6. ATP (adenosine triphosphate) molecule used in energy. • When has phosphate group - like loaded spring; when loses phosphate group, energy released. • Energy comes from conversion of ATP to ADP and inorganic phosphate (Pi). • Animal cells can regenerate ATP back from Pi and ADP by breaking down organic molecules.

  7. http://www.med8th.com/nobel/winners/1992/1992-phosphorylation.jpghttp://www.med8th.com/nobel/winners/1992/1992-phosphorylation.jpg

  8. Movement of end phosphorus group from one molecule to another - phosphorylation. • Temporarily changes shape of molecule; changes back to original shape when phosphate leaves.

  9. Redox reaction - electrons transferred from 1 reactant to another. • Loss of electrons - oxidation. • Addition of electrons - reduction. • Electron donor - reducing agent; electron recipient - oxidizing agent.

  10. http://www.emc.maricopa.edu/faculty/farabee/BIOBK/redox.gif

  11. Respiration is a redox reaction. • Glucose oxidized, oxygen reduced, electrons lose potential energy.

  12. http://bioweb.wku.edu/courses/BIOL115/Wyatt/Metabolism/Respiration.gifhttp://bioweb.wku.edu/courses/BIOL115/Wyatt/Metabolism/Respiration.gif

  13. At key steps, hydrogen atoms stripped from glucose, passed 1st to coenzyme (i.e. NAD+) • Turns NAD+ into NADH.

  14. NADH shuttles electrons from food to “top” of chain. • At “bottom,” oxygen captures electrons and H+ to form water.

  15. http://kvhs.nbed.nb.ca/gallant/biology/etc.jpg

  16. 3 stages in respiration: glycolysis, Krebs cycle, electron transport chain and oxidative phosphorylation. • Glycolysis – cytoplasm; Krebs cycle - mitochondrial matrix.

  17. Glycolysis and Krebs cycle - electrons passed from substrates to NAD+, forming NADH. • NADH passes electrons to electron transport chain (ETC). • In ETC electrons move from molecule to molecule until they combine with O2 and H+ ions to form water.

  18. http://www.biology.lsu.edu/introbio/spring/Spring%202005/1001/SMP/Overall%20summary%20of%20Glycolysis%20and%20the%20Krebs%20Cycle.jpghttp://www.biology.lsu.edu/introbio/spring/Spring%202005/1001/SMP/Overall%20summary%20of%20Glycolysis%20and%20the%20Krebs%20Cycle.jpg

  19. During ETC energy carried by electrons stored in mitochondrion in form used to synthesize ATP via oxidative phosphorylation. • ATP also generated in glycolysis and Krebs cycle by substrate-level phosphorylation. • Enzyme transfers phosphate group from organic molecule (substrate) to ADP, forming ATP.

  20. * • 38 ATP produced per mole of glucose - broken down to CO2 and H2O by respiration. • 34 ATP made through oxidative phosphorylation , 4 ATP from substrate-level phosphorylation giving 38 total ATP molecules.

  21. http://www.nismat.org/physcor/atp.gif

  22. During glycolysis, glucose, 6-C sugar split into (2) 3-C sugars. • Net yield from glycolysis 2 ATP and 2 NADH per glucose. • Glycolysis occurs whether O2 present or not. • O2 present, pyruvate moves into Krebs cycle.

  23. More than ¾ of original energy in glucose still present in 2 molecules of pyruvate. • Pyruvate first modified into acetyl CoA (actually enters Krebs cycle) • Each turn of Krebs cycle produces 1 ATP, 3 NADH, 1 FADH2 (electron carrier) for every molecule of acetyl CoA.

  24. Most ATP generated during respiration comes from energy in electrons carried by NADH (and FADH2). • Energy in these electrons used in ETC to make ATP.

  25. http://www.stanford.edu/group/hopes/treatmts/ebuffer/f_j03nadhrole.gifhttp://www.stanford.edu/group/hopes/treatmts/ebuffer/f_j03nadhrole.gif

  26. As electrons move down ETC they pass energy. • Transported by either NADH or FADH2.. • Purpose of ETC - break up energy into smaller amounts - released in smaller amounts.

  27. ATP synthase makes ATP from ADP and Pi. • ATP synthesis generated through proton gradient produced by movement of electrons along ETC. • Gradient made when there is higher concentration in one area.

  28. Several chain molecules use flow of electrons to pump H+ from matrix to intermembrane space. • Concentration of H+ - proton-motive force.

  29. ATP synthase molecules only place that allow H+ to diffuse back to matrix of mitochondria. • Coupling ETC with ATP synthesis called chemiosmosis - helps generate ATP.

  30. http://fig.cox.miami.edu/~cmallery/150/makeatp/chemiosmosis.jpghttp://fig.cox.miami.edu/~cmallery/150/makeatp/chemiosmosis.jpg

  31. Glycolysis produces 2 ATP whether or not O2 present. • O2 present, additional ATP generated when NADH delivers electrons to ETC. • If no O2 present - process fermentation.

  32. http://www.mr-damon.com/experiments/2sp/projects/images/fermentation.jpghttp://www.mr-damon.com/experiments/2sp/projects/images/fermentation.jpg

  33. If NAD+ present, electrons accepted whether or not O2 present. • During fermentation, ATP generated by glycolysis; NAD+ recycled by transferring electrons from NADH to pyruvate. • Aerobic conditions, NADH transfers electrons to ETC, recycling NAD+.

  34. http://www.botany.unibe.ch/deve/images/ethferm1.gif

  35. Alcohol fermentation, pyruvate converted to ethanol in 2 steps. • 1st, pyruvate converted to 2-C compound (acetaldehyde) by removal of CO2. • 2nd, acetaldehyde reduced by NADH to ethanol (used in brewery).

  36. Lactic acid fermentation, pyruvate reduced directly by NADH to form lactate (form of lactic acid). • Muscle cells switch from aerobic respiration to lactic acid fermentation to generate ATP when O2 is scarce. • Waste – lactate; buildup causes muscle soreness.

  37. Aerobic respiration, 38 ATP generated (2 produced through anaerobic respiration for 1 molecule of glucose). • Some organisms (facultative anaerobes), including yeast, bacteria, survive using either fermentation or respiration.

  38. Glycolysis can occur with many organic molecules. • If not carbohydrate - must be broken down 1st. • Fats give 2x as much ATP as carbohydrates.

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