Biolo1100 Chapter 7 How Cells Harvest Energy from Food
  1. Metabolism involves the transformation of potential   energy into kinetic   energy in living things, and comprises photosynthesis   and cellular respiration  .

     
  2. Cellular respiration is composed of two stages: glycolysis occurs in the cytoplasm   while the Krebs cycle occurs in mitochondria  .

     
  3. In glycolysis, glucose   is broken down into two three-carbon pyruvate   molecules, yielding a net of two   molecules of ATP per glucose.

     
  4. In aerobic   conditions (with oxygen), pyruvate is further broken down to make more ATP.
     
    • The pyruvates are passed into the mitochondrion   where they are converted into acetyl-coA, which enters the Krebs   cycle.

       
    • In the Krebs cycle, each acetyl-coA yields one   molecule of ATP, and several molecules of NADH   and FADH2.

       
    • The energy stored in NADH   and FADH2 is harvested by the electron   transport chain (ETC) to make ATP  .




     
  5. In anaerobic   conditions, glycolysis is followed by fermentation  , which regenerates the electron receptor NAD+, and allows glycolysis   to continue generating ATP.





     
  6. Other macromolecules such as proteins   and fats   can also enter cellular respiration via different pathways.

     
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