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Respiration B.9

Respiration B.9. Overview energy is required for all cellular work most organisms produce ATP by using energy stored in the bonds of organic molecules such as carbohydrates (mostly glucose), fats, and proteins exothermic process (-ΔG)

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Respiration B.9

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  1. Respiration B.9

  2. Overview • energy is required for all cellular work • most organisms produce ATP by using energy stored in the bonds of organic molecules such as carbohydrates (mostly glucose), fats, and proteins • exothermic process (-ΔG) • most respiration is aerobic (use O2) and some is anaerobic (does not use O2)

  3. Aerobic Respiration • oxidation of food, such as glucose, to produce carbon dioxide, water, and energy (36 ATP) • occurs in three main phases that happen through many gradual reactions 1. Glycolysis 1½. The Link Reaction 2. The Citric Acid (Kreb’s) Cycle 3. ETS (Electron Transport System)

  4. Link Reaction

  5. Anerobic Respiration • respiration carried out in the absence of oxygen • purpose is to oxidize NADH back to NAD+which is recycled back for glycolysis • meaning it keeps glycolysis going and therefore only makes 2 ATP • end products are alcohol or lactic acid • two methods…

  6. glucose →energy (ATP) + ethanol + carbon dioxide (CO2) • Alcoholic fermentation • common with bacteria and yeast (fungi) • the pyruvates from glycolysis are transformed into ethyl alcohol (toxic to organism) • CO2isgiven off • process is energetically wasteful because so much of the free energy of glucose (some 95%) remains in the alcohol (a good fuel)

  7. glucose →energy (ATP) + lactic acid 2. Lactate Fermentation • occurs in bacteria and animal muscle tissue • the pyruvates from glycolysis are converted to lactate (lactic acid) • energetically wasteful because so much free energy remains in the lactic acid molecule • it can also be debilitating because of the drop in pH of overworked muscles

  8. Role of Cu and Fe in electron and oxygen transport (B.9.2) • The electron transport system accepts hydrogen atoms and passes their electrons from one member of the chain to the next • It is a series of redox reactions involvingthe transport of electrons. • Cytochromes- • Oxidizing Enzymes • Consisting of a protein ,a porphyrin ring, a copper or iron ion (Cu2+, Fe2+)

  9. Cyto-chrome Structure 20

  10. Cytochromes Contain Cu2+ or Fe3+ ions. The porphyrinligand contains 4 nitrogen atoms, each of which donates 2 electrons. Oxidation Stage C6H12O6 + 6H2O  6CO2+24H+ +24e- Fe 3++ e- Fe 2+ (Metal ion is reduced) Cu 2+ + e- Cu + Reduction stage O2 + 4H+ +4e-  2H2O Fe 2+ Fe 3+ + e-(Metal ion is oxidized) Cu + Cu 2+ + e- 21

  11. Cytochrome Oxidase

  12. Role of Haemoglobin in Cellular Respiration. • Respiratory pigment that carries oxygen in the blood during respiration • Contains a heme group with an iron atom a its center. • Iron atom binds to O2 in lungs • When Hb is oxygenated it appears bright red. • Hb carries O2 through the blood stream to cells in the body. At high carbon dioxide concentrations as are found at the cell level hemoglobin releases O2 to the cells. Hemoglobin binds to the carbon dioxide molecules which are then transported back to the lungs where the carbon dioxide is exhaled. Carbon monoxide (CO) and cyanide (CN-) are poisonous because they form irreversible complex ions with the iron –preventing it from carrying oxygen. Contains 4 large polypeptide units and 4 Fe atoms each surrounded by a porphyrin ligand. This is the heme (haem) group.

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