Respiration and Cellular Activities: 5.8, 5.9, 5.10


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Respiration and Cellular Activities: 5.8, 5.9, 5.10

  1. 1. Respiration and Cellular Activities
  2. 2. 5.8:The Krebs Cycle in Fat and Protein Metabolism <ul><li>Cells use the fatty acids of fats for energy </li></ul><ul><ul><li>Enzymes in the mitochondria break down the fatty acids to acetate </li></ul></ul><ul><ul><ul><li>(transported to the K-Cycle by CoA) </li></ul></ul></ul><ul><ul><li>The K Cycle breaks down the acetate in the same way as sugars </li></ul></ul><ul><ul><li>Without oxygen, most of the energy in fat can NOT be transferred to ATP because the fatty acids bypass glycolysis </li></ul></ul>
  3. 3. 5.8 (cont.) <ul><li>Proteins in respiration </li></ul><ul><ul><li>Digestive enzymes first break down protiens to amino acids  removed by other enzymes (produces ammonia  converted to safer N-compounds  recycled/excreted) </li></ul></ul><ul><ul><ul><li>Left over C-skeletons undergo reactions to form 4- or 5-C acids (oxaloacetate/ketoglutarate  K Cycle) </li></ul></ul></ul>
  4. 4. carbohydrates glycolysis C-C-C (pyruvate) C-C CoA lipids fatty acids C-C-C-C-C C citrate C-C-C-C-C ketoglutarate C-C-C-C oxaloacetate Krebs Cycle
  5. 5. 5.8 (cont) <ul><li>The K Cycle and glycolysis provide building blocks for biosynthesis </li></ul><ul><ul><ul><li>Autotrophs: the pathways + the Calvin cycle lead to the synthesis of every organic compound the organism needs </li></ul></ul></ul><ul><ul><ul><li>Heterotrophs: the pathways lead to most of the necessary organic compounds (must consume organic compounds they can’t synthesize: vitamins, certain amino acids, certain fatty acids) </li></ul></ul></ul>
  6. 6. 5.8 (cont) <ul><li>Most synthesis pathways are not the reverse of decomposition pathways </li></ul><ul><ul><li>Separate enzymes and pathways lead to more efficient operation (cells synthesize proteins by a very precise system) </li></ul></ul><ul><ul><ul><li>Digestion is NOT precise: enzymes break the bonds b/w amino acids until the protien is completely decomposed ( hydrolysis : the components of water (H and OH) are inserted into the bonds to break them) </li></ul></ul></ul>
  7. 7. 5.8 (cont) <ul><li>Most biological decomopositions involve hydrolysis </li></ul><ul><ul><li>Enzymes hydrolysis simple sugars and fats  fatty acids and glycerol </li></ul></ul><ul><ul><li>Cells in the intestines use active transport to get the amino acids, sugars, and nutrients into the bloodstream </li></ul></ul>
  8. 8. 5.9: Respiration and Heat Production <ul><li>All chemical reactions release heat energy </li></ul><ul><ul><li>Respiration keeps us warm (homeostatic mechanism) </li></ul></ul><ul><li>Some mammals have “brown fat” </li></ul><ul><ul><ul><li>Contains more mitochondria than other tissue  adapted for rapid production of thermal energy (stored fat is used in respiration, producing little ATP and lots of heat energy: important for hibernation/hairless animals) </li></ul></ul></ul>
  9. 9. 5.9 (cont) <ul><ul><ul><li>Brown fat is located on the neck and between the shoulders </li></ul></ul></ul><ul><li>Some plants have evolved a form of respiration that produces lots of heat energy </li></ul><ul><ul><li>Mitochondria have an alternate branch of the e - ts </li></ul></ul><ul><ul><ul><li>Some of the energy of electron flow results in more heat energy and less ATP </li></ul></ul></ul><ul><ul><ul><ul><li>Become too hot to touch  organic compounds evaporate  give off the odor of rotting meat  attracts flies and beetles, used to pollinate the flower </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Ex. Skunk cabbage </li></ul></ul></ul></ul></ul>
  10. 10. 5.10: Control of Respiration <ul><li>Rate of respiration must be controlled to direct energy and C-skeletons accurately to the pathways and cells where they are needed </li></ul><ul><ul><li>Control  organization  survival </li></ul></ul><ul><li>Is glucose broken down in respiration or converted to starch/fat? </li></ul><ul><ul><li>Mechanisms decide by supply-and-demand </li></ul></ul>
  11. 11. 5.10 (cont) <ul><li>If animals use energy rapidly (high demand for energy)  cells absorb glucose from blood to produce ATP=low blood sugar </li></ul><ul><ul><li>Liver breaks down stored glycogen to restore blood sugar levels </li></ul></ul><ul><li>Low demand for energy  cells use excess glucose synthesize glycogen  fat </li></ul>