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Homework Help: How do catabolic reactions drive anabolic reactions

  1. May 23, 2016 #1
    1. The problem statement, all variables and given/known data
    Explain how a cell can use catabolic reactions to drive anabolic reactions, despite energy loss in the form of entropy and heat.
    2. Relevant equations
    Catabolic Pathway: A series of reactions that results in the breakdown of larger,more-complex molcules into small, less complex molecules releasing energy in the process
    Anabolic Pathway: Opposite of Catabolic Pathway
    Change in Free Eneryg=ΔG=ΔH-TΔS where H is the enthalpy and S is the entropy.

    3. The attempt at a solution
    Since catabolic reactions release energy, this new energy can be used in anabolic reactions. The main question,however, is how do I know this is chemical energy that can be used? How do I not know this is energy is not lost due to heat? I believe this reason has to do with the fact there is negative ΔG for catabolic reactions meaning there is less free energy in the products, but I don't entirely understand how this shows there is potential energy to spare.
  2. jcsd
  3. May 24, 2016 #2


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    Staff: Mentor

    Part of the energy is always lost as heat.

    Does it have to be all energy that is lost?

    Think about a car. The engine gets hot, the exhaust gases are hot, yet it moves.
  4. May 24, 2016 #3


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    Homework Helper
    Gold Member

    if the question is how it happens, you will have to go to the library and find the most elementary textbook on biochemistry (unless you have one or a chapter). Maybe start with synthesis (anabolic) of something simple like polysaccharides (e.g. glycogen, starch). Just one example , otherwise it's too much. Then find out where the stuff needed for the synthesis comes from. You will be looking at stuff like ATP, oxidative phosphorylation,...
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