Khan academy 1

Catalyst

A substance that speeds up a chemical reaction, without being a reactant

Enzymes

Catalysts for biochemical reactions in living organisms

Enzymes are usually

Proteins, RNA molecules

Activation energy

The amount of energy needed for a reaction to begin

Enzymes impact on activation energy

Lowers

How enzymes work

Binds to reactant molecules and creates optimal positioning, also bends and stresses bonds weakening them

Free energy

Amount of energy available to do work

Enzymes impact on free energy

Does not change it

Substrates

Reactant molecules enzymes bind on to

Active site

The part of the enzyme where the substrate binds

Properties of active site

From amino acids

Active sites shape, size, and chemical behavior

Determined by set of amino acids and their tertiary structure

Factors that impact active site and enzyme’s function

Temperature, pH, enzyme concentration, substrate concentration

Induced fit

An enzyme slightly changing shape when binding to a substrate

Ways activation energy is lowered

• bringing two substrates together in right orientation

• creating environment inside active site favorable to reaction

• bending substrate molecules

• forming temporary covalent bonds with substrate molecules