What are enzymes?  What is there function?
· Protein substances that are necessary for most of the chemical reactions that occur in living cells.
· Act as a catalyst for these reactions

What is a catalyst?
· A substance that brings about a reaction without changing itself.
· Enzymes are considered organic catalysts.

What is a substrate?
· A substance that an enzyme acts upon.
· The name of an enzyme comes from the substrate with and -ase on the end   ex. lactase, proteases, maltase

What is the active site?
· A region on the enzyme that fits a particular shaped substrate and only that substrate.

There are two ways to explain how enzymes work.  Explain both and provide a sketch of each

Lock and Key -
· A certain enzymes fits a certain substrate and opens it like a key opens a lock.

Induced-fit model -
· Same as lock and key model except the enzyme conforms and takes the shape of the substrate. 
· Molds around the substrate and loosens it up.
· Only one enzyme for each type of substrate

Explain the six factors that affect enzyme action.
· Small amounts of an enzyme can work on large amounts of substrate.  Enzymes can be used over and over.
· Enzymes allow reactions to take place at normal temperatures.  Speeding the reaction without heat, which would kill cells.
· Enzymes work best at certain temperatures. Low temperature cause reactions to slow down, while high temperature cause the enzyme to become deformed (denatured)
· Enzymes work best at a certain pH.  The pH depends on the surrounding environment. 
· The rate of an enzyme-controlled reaction depends on how much of the enzyme and the substrate there are.  It also depends on how much of each comes in contact with one another.  Once all substrate molecules are occupied dumping in more enzyme will not speed the reaction.
· Some enzymes need additional substances to work.  These are called coenzymes.  Ex. vitamins