ENZYME NOTES
Chemical Reactions
Chemical Reaction – process that changes
one set of chemicals into another set of
chemicals
 Reactants – elements or compounds that
enter into a chemical reaction
 Products – elements or compounds
produced by a chemical reaction
 Example: 2H2 + O2 
2 H2O

Reactants
Product

Chemical Reactions
 Chemical
reactions always
involve the breaking of bonds in
reactants and the formation of
new bonds in products
 Energy is released or absorbed
whenever chemical bonds form or
are broken
Enzymes
Catalyst – substance that speeds up the
rate of a chemical reaction
 Enzymes – proteins that act as biological
catalysts (speed up chemical reactions
that take place in cells)
 Enzymes help lower the activation
energy of a chemical reaction (the
energy needed to get a reaction started)

Enzymes
 The
reactants of enzymecatalyzed reactions are known
as substrates
 Substrates bind to a site on
the enzyme called the active
site
Substrate
Active Site
Enzyme
Products
Enzymes
 The
fit between the active site and
substrates is so precise that it is often
compared to a lock & key