Metabolism and enzymes Mader Biology Chapter 6

Metabolism

ATP is the cell’s source of energy

Reactions can be endergonic or exergonic Exergonic (exothermic) Endergonic (endothermic) Releases energy ATP  ADP + P Absorbs energy ADP + P  ATP

Coupling Living systems couple endergonic with exergonic reactions

Kinetic Energy vs Chemical Energy Kinetic Energy Chemical Energy Energy of movement Energy stored in bonds

Enzymes

Enzymes Functional proteins Used to catalyze chemical reactions They do this by decreasing the amount of activation energy needed for the reaction to occur

Anatomy of an Enzyme Substrate binds at the active site

Enzymes Don’t get changed or used up in the reaction Work on highly specific substrates Substrate attaches to Active Site with of the enzyme and is converted to product

Competitive vs. Non-competitive Inhibition COMPETITIVE INHIBITOR: Takes the place of the normal substrate Does not change the ‘shape’ of the active site Usually reversible NON-COMPETITIVE INHIBITOR: Attaches to the allosteric site (different than the active site) Changes the shape of the enzyme, and thereby the active site. Many are non reversible.

Factors affecting Enzymes Many will not work properly without Cofactors (inorganic- ex: Zn, Fe) or Coenzymes (organic). Most coenzymes are vitamins or vitamin derivatives Denaturation: pH Temp Salinity