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What Actually Happens During Digestion?

  1. Aug 5, 2012 #1
    What actually happens when cells break down food and combines it with oxygen? Does the sugar release a particle or energy in the form of light? If a particle, what is happening? Does the release of energy transform two different particles (one is the sugar, the other being the one that receives the energy)? Explain in layman's terms please.
  2. jcsd
  3. Aug 5, 2012 #2
    are you asking digestion or sugar metabolism. The average glucose starts with 6 carbons, then 3 carbons and then CO2 as the end product. There is no light, energy is stored in the form several reducing molecules and the rest lost in the form of heat.
  4. Aug 5, 2012 #3
    Most of the energy released from oxidizing glucose is stored as chemical energy in the molecule called adenosine triphosphate (ATP). Most of the cells metabolic processes use energy released when adenosine triphosphate loses a phosphate group to become adenosine diphosphate (ADP), or adenosine monophosphate (AMP).
    The formation of ATP occurs in the cell, usually in the mitochondria. The ATP travels to other parts of the cell, to provide energy. ATP has been called the "energy currency of the cell". Whenever respiration occurs, some fuel gets oxidized. As far as the cell is concerned, the most important part of the respiration process is the formation of ATP.
    Here is a link regarding ATP.
    “The overall process of oxidizing glucose to carbon dioxide is known as cellular respiration and can produce about 30 molecules of ATP from a single molecule of glucose.[23] ATP can be produced by a number of distinct cellular processes; the three main pathways used to generate energy in eukaryotic organisms are glycolysis and the citric acid cycle/oxidative phosphorylation, both components of cellular respiration; and beta-oxidation. The majority of this ATP production by a non-photosynthetic aerobic eukaryote takes place in the mitochondria, which can make up nearly 25% of the total volume of a typical cell.”
  5. Aug 9, 2012 #4


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    Your question as elaborated was about the whole of energy metabolism; Darwin has given you as good an answer as you can reasonably expect here, - you need a couple of chapters at least of almost any book of general biochemistry.

    Strictly physiologists and biochemists reserve the term 'digestion' to mean just the first part of the process: the chemical breaking down in the digestive tract, mainly stomach, of complex molecules like proteins and polysaccharides into simpler soluble ones such as amino acids and monosaccharides which can then be absorbed into the bloodstream. This absorbtion is already considered a different process to digestion.
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