General ---------Biology---------------------------------------------------- ------------------Online----------------------------------wilcox@sunline.net Ch. 6  Metabolism of carbohydrates, fats, proteins, nucleic acids

Imagine 10,000 starch molecules in a test tube.  Every so often one to two of the molecules might gain enough kinetic energy to break a covalent bond and release a sugar molecule from the chain.  But most of the molecules lack sufficient energy to "spontaneously" break apart; most of the molecules cannot surmount the "energy barrier."  If you warm the starch, more molecules could surmount the energy barrier, and if you cool it fewer molecules will. 

The Figure below illustrates this energy barrier, and enzymes allow more molecules to surmount the energy barrier by "lowering"it.  For a discussion of how enzymes accomplish this magic, click here.