Metabolism

Energy of Life

Metabolic Pathways

Anabolic Pathways Catabolic Pathways

Kinetic Energy

Potential Energy

First Law of Thermodynamics

Energy can be transferred or transformed but it cannot be created or destroyed

Second Law of Thermodynamics

Every energy transfer or transformation increases the entropy of the Universe

Free Energy

Gibbs Equation

G = H – TSG – Change in Free energy

H – Change in Total energy

T – Absolute temperature in Kelvin

S – Change in Entropy

Free Energy and Metabolism

Free Energy and MetabolismExergonic Reactions

Release of energy

-G

Spontaneous

Downhill

More energy in reactants than in products

Ex. Cellular Respiration• -686 kcal/mol

Ex. ATP ADP + P• -7.3 kcal/mol

Endergonic ReactionsAbsorbs energy

+G

Nonspontaneous

Uphill

More energy in products than in reactants

Ex. Photosynthesis• +686 kcal/mol

Ex. ADP + P ATP• +7.3 kcal/mol

Enzymes

Biological Catalyst

Speed up metabolic reactions by lowering the energy of activation

Enzymes

Substrate Specific

Active Site

Induced Fit

Recycled

Enzymes

InhibitorsCompetitive

Noncompetitive

Enzymes

Allosteric Sites

Cooperativity

Feedback Inhibition

Pathway switched off