Enzymes are proteins that function as catalysts in living organisms. They speed up chemical reactions by lowering their activation energy, allowing reactions to take place at lower temperatures. Enzymes catalyze reactions by binding to specific substrates at their active sites, bringing substrates together or twisting them to weaken bonds for reactions. Metabolism consists of both catabolic reactions that break down molecules to release energy and anabolic reactions that use energy to build up molecules, and enzymes regulate these metabolic reactions through catalysis.

1. All about Enzymes

2. Objectives:
 To define catalyst and
describe how enzymes
function as catalysts
in living organisms

3. A substance that altersA substance that alters
the rate of a chemicalthe rate of a chemical
reaction without itselfreaction without itself
being changed or usedbeing changed or used
upup
Catalyst

4. Enzymes – proteins that are
catalysts in cells
1) speed up a reaction by
lowering activation energy
2) allow reactions to take
place at lower
temperatures
3) Regulate Metabolism

6. MetabolismMetabolism
 CatabolismCatabolism -”breakdown” of large
molecules into smaller units to release
energy.
 Example: Polysaccharide 
Monosaccharide
 AnabolismAnabolism - "building up" of
molecules and materials (organs,
tissues) by using energy.
 Example: Glucose  Glycogen

7. AnabolismAnabolism + Catabolism =+ Catabolism = MetabolismMetabolism
The SUMSUM of all
chemical reactions!

9. substrate – The
substance affected
by an enzyme.
active site – region on an
enzyme that can bind with a
specific substrate.
Ex. Lactase binds to Lactose

10. substrate

12. Ways in Which Enzymes
Catalyze Chemical Reactions
Ways in Which Enzymes
Catalyze Chemical Reactions
1) holding two substrates in positions in
which they can react with each other
2) twisting a substrate molecule slightly
so that a chemical bond is weakened
and broken