L10_Chp7_notes

L10_Chp7_notes - How Cells Release Chemical Energy -Chapter...

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How Cells Release   Chemical Energy  --- Chapter 7 Producing the Universal Currency of Life  All energy-releasing pathways, require characteristic starting materials, yield predictable  products and by-products and produce ATP  ATP Is Universal Energy Source Photosynthesizers get energy from the sun Animals get energy second- or third-hand from plants or other organisms Regardless, the energy is converted to the chemical bond energy of ATP Making ATP Plants make ATP during photosynthesis Cells of all organisms make ATP by breaking down carbohydrates, fats, and protein Main Types of Energy-Releasing Pathways  Anaerobic pathways -- Evolved first; Don’t require oxygen;   Start with glycolysis in cytoplasm;  Completed in cytoplasm Aerobic pathways  Evolved later; Require oxygen; Start with glycolysis in cytoplasm; Completed in mitochondria Energy-Releasing Pathways Overview of Aerobic Respiration C 6 H 12 0 6      +         6O 2                 6CO 2            +        6H 2 0      glucose       oxygen                    carbon dioxide          water Main Pathways Start with Glycolysis  Glycolysis occurs in cytoplasm Reactions are catalyzed by enzymes
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Glucose     ---------- 2 Pyruvate  (six carbons)             (three carbons) The Role of Coenzymes NAD +  and FAD accept electrons and hydrogen from intermediates during the first two stages When reduced, they are NADH and FADH 2   In the third stage, these coenzymes deliver the electrons and hydrogen to the transfer chain Overview of Aerobic Respiration Glucose   Is a simple sugar   (C 6 H 12 O 6 ) Atoms are held together by covalent bonds  Glycolysis Occurs in Two Stages  Energy-requiring steps  ATP energy activates glucose and its six-carbon derivatives Energy-releasing steps  The products of the first part are split into three-carbon pyruvate molecules ATP and NADH form  Energy-Requiring Steps   Energy-Releasing Steps Net Energy Yield from Glycolysis   Energy requiring steps:    2 ATPs are invested or expended Energy releasing steps:    2 NADH   and 4 ATP formed  Net yield is 2 ATP and 2 NADH
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This note was uploaded on 03/20/2008 for the course BI SC 001 taught by Professor Schlegel during the Spring '99 term at Penn State.

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L10_Chp7_notes - How Cells Release Chemical Energy -Chapter...

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