ENZYMES
Mrs. Kezia Chi
Objectives
DISCUSS WHAT IS AN
ENZYME
DEFINE CATALYST
LIST THE 3 MAIN TYPES
OF DIGESTIVE ENZYME
What are they?
◦Enzymes
◦ Are protein catalysts that allow chemical reactions to
take place in our body without increasing the
temperature
◦ End with the suffix ‘-ase’
◦ Examples: urease, amylase, sucrase
Catalyst
◦ Control the speed of reactions without changing the
products formed.
◦ It increases the rate of a chemical reaction.
Enzymes
◦ Work on molecules called the
substrate
◦ Can be anything Carbohydrates- glucose, sucrose,
starch, etc.
 Amino acids, peptides, proteins
 Fatty acids
◦ Are substrate-specific
◦ Alter the substrate in some way
Enzyme models
◦ Where the substrate joins the enzyme is
called the active site
◦ ‘Lock and Key Model’
◦ The active site of an enzyme is a perfect
match to a specific substrate
◦ The place where these molecules fit is called
the active site .
◦ In the lock and key model, the shape of the
active site matches the shape of its substrate
molecules. This makes enzymes highly
specific.
Lock and Key Model
Enzymes in
Digestion
Digestive Enzymes
◦ There are 3 main types of digestive enzymes:
◦ Amylase- breaks starch down into glucose
◦ Protease- breaks protein down into amino acids
◦ Lipase- breaks fats down into fatty acids and glycerol
Digestive Enzymes and Their
Specific Role