AND CHEMICAL REACTIONS

REACTIONS atoms must be balanced on both sides of the equation in a chemical reaction Balance the following equation: Reactants Products CO2 + H2O → C6H12O6 + O2 6CO2 + 6H20 → C6H1206 + 6O2

2 TYPES OF CHEMICAL REACTIONS 1. Exothermic: Release Energy – can occur spontaneously give off energy

Example – digestive process releases energy from food Energy-Releasing Reaction Activation energy Reactants Products

2. Endothermic: Absorb Energy – need energy to occur store energy Example – photosynthesis Energy-Absorbing Reaction Activation energy Reactants Products

Energy needed to start a reaction is called activation energy.

Provides a place for reactants (substrates) to react (active site) HOW AN ENZYME WORKS Provides a place for reactants (substrates) to react (active site) Active site They fit together with the enzyme like a lock and key forming an enzyme-substrate complex.

Enzymes are specific in their activity. Enzymes lower the activation energy. Enzymes speed up the rate of a reaction.

When the reaction is complete, the products are released and the enzyme remains unchanged and reusable.

ENZYME REGULATION 1. Change in temperature or pH can affect the enzyme.

Some enzymes (allosteric enzymes) can be turned on or off by other proteins by changing the enzyme’s shape.