Lesson 9 - Proteins as Enzymes
Student Performance Objectives
1. Define catalyst, enzyme, substrate, product and metabolic pathway.
2. Distinguish between extracellular and intracellular enzymes.
3. List and describe 5 conditions that affect the work of enzymes.
4. Define isozyme and explain their diagnostic usefulness.
5. Explain the concept of an enzyme's active site.
6. Explain why it is important for an enzyme to lower the activation energy for a
A. Enzymes as biological catalysts. Animations of enzyme actions:
B. Enzymes as molecular machines carrying out a very specific activity.
C. Enzymes working in sequences, as machines in a factory, converting a starting material,
called the substrate, into a finished product.
D. Functional enzyme sequences called metabolic pathways.
E. Enzyme types.
1. Extracellular (e.g., digestive like amylase and pepsin).
2. Intracellular (e.g., glycolytic and Kreb's cycle enzymes).
F. Condition affecting the work of enzymes.
2. Substrate (reactant) concentrations.
4. Salt concentration.
5. Presence of correct concentrations of coenzymes (usually "B" vitamins) and
(usually minerals, also called metals, like magnesium, Mg+2).
6. Presence of inhibitory, inorganic substances, e.g., heavy, toxic metals like
mercury, Hg, or lead, Pb.
7. Presence of inhibitory organic substances, e.g., various carbon-based molecules
used in insecticides
G. Enzyme variations by tissue: isozymes and diagnostics for heart, liver and kidney
H. Theory of enzyme function: providing surface for substrate interactions (the enzyme's
site) and lowering of the activation energy necessary for the substrates to chemically
with each other.