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

Return to glycolysis, Fig. 9.9 in text, and determine the substrate, enzyme and product for Step 1:
substrate ____________________
enzyme   ____________________
product  ____________________

"Enzyme," a molecule that catalyzes a specific chemical reaction.  Each enzyme is specific to one reaction and no other.  An enzyme is not used up in the reaction and can catalyze the same reaction over and over.  An enzyme's name end in "ase," and their name describes what they do.  An enzyme that removes a hydrogen from a molecule would be named "dehydrogenase."

What would be a fitting name for an enzyme that removes a carboxyl (functional group) from a molecule?  __________________________________

"Substrate" is the molecule being acted on, or entering the active site of the enzyme, like a key enters a lock. The active site is a "hole," grove or recess in the enzyme that is the exact shape of the substrate molecule... "fits like a lock and key." "Product" is the molecule leaving the enzyme's active site after being modified by the enzyme.

Lock and Key Analogy. The key fits the key hole in the lock as the _____________ fits the _____________ in the enzyme.

To abbreviate the reaction in the figure above, we substitute the word "enzyme" for the actual molecule, and draw the reaction as shown below.  This one reaction would be one step in a metabolic pathway. 

One step in a pathway can be illustrated as a formula:

	__________________
chemical A		chemical B
_____________	(is converted into)	______________