AP Bio Unit 3 - Cellular Energetics

1st law of thermodynamics

Energy cannot be created or destroyed, only transformed from one form to another.

2nd law of thermodynamics

Energy transformation increases the entropy(measure of disorder) of the universe - when energy is converted some energy is lost heat

Metabolism

the sum of all chemical reactions in a cell that transforms energy and matter

Metabolic Pathways

Series of linked chemical reactions that either break down complex molecules or build complex molecules - pathways are sequential 

Catabolic Pathways

Pathways that break down complex molecules and this releases energy

Anabolic Pathways

Pathways that build complex molecules from simpler compounds and this requires energy

Endergonic

Need energy

Exergonic

Release energy

Coupling reactions

Cells carry out energy needing reactions by coupling them to ATP hydrolysis

Regeneration of ATP

ADP can be regenerated to ATP by the ATP cycle 

Enzymes

proteins that catalyze (speed up) reactions by lowering activation energy needed to start a reaction

Enzyme Structure

Enzymes react on reactants called substrates and bind to active site

Enzyme Function

Enzymes break down complex molecules and build complex molecules 

Enzyme Cofactors

Some enzymes consist only of polypeptide chains and others require cofactors - nonprotein molecules that bind enzymes and assist enzyme function