Worksheet for Topic5 Enzymes
5.1 Biological catalysts

Enzymes are catalysts that speed up the rate of a chemical reaction without being
changed or used up in the

Enzymes are proteins

Enzymes are biological

Enzymes are specific
reaction.
.
catalysts.
（特异的，专一的） to one particular substrate （底物）
as the enzyme is a complementary

（互补的）shape to the substrate.
Enzymes are necessary to all living organisms as they maintain reaction speeds of all
metabolic
reactions (all the reactions that keep an organism alive) at a rate that
can sustain life.

Naming enzymes= substrate + -ase
Enzyme
Substrate
Protease
Lipase
Carbohydrase
Maltase
Amylase
5.2 Properties of enzymes
(1) Effect of temperature on enzymes
Enzymes work best at a particular
Enzymes are denatured
temperature.
at high temperature.
(2) Effect of pH on enzymes
Enzymes work best at a particular
Enzymes are denatured at extreme
pH.
pH.