Energy & Enzymes

Miss Napolitano & Mrs. HaasCP Biology

Metabolism & Energy

Metabolism: the total of all chemical reactions that take place within an organism

Energy: the capacity to do work Kinetic energy: energy in motion

Potential energy: stored energy

Chemical Reactions Absorb or Release

Energy Exergonic reaction: releases free energy Products contain less energy than the

reactants

Energy exits

Example: cell respiration

Endergonic reaction: absorbs free energy Products contain more energy than the

reactants

Energy enters

Example: photosynthesis

Exergonic vs. Endergonic

Ea = Activation Energy = the energy required to start the reaction

Exergonic Endergonic

Catalysts Catalyst: reduces the activation energy to

speed up the chemical reaction

Enzyme: catalytic protein

End in -ase

1. Specific substrate binds to the active site on an enzyme

2. Enzyme reduces Ea

3. Reaction occurs, products are formed

4. Enzymes can be reused

Enzyme-Substrate Complex

Effect of Enzymes on Reaction Rate

External Factors can Affect Enzyme

Activity Factors that affect enzyme shape will

affect its function Ex: temperature, pH

Different enzymes have different optimal conditions

Enzyme Inhibitors Inhibitors prevent an enzyme from

catalyzing a reaction Can block substances from entering the

active site

Can bind to another part of the enzyme, causing the enzyme to change shape & become inactive