Enzymes

Catalysts – speed up reactions without being used up or changed by the reaction

Why is heat a bad catalyst for living systems? Damages cells Not specific

Activation energy – amount of energy needed to get a reaction started The amount of energy needed to break the bonds of the reactants

Enzymes are biological catalysts - Proteins – very specific shapes - Usually end in –ase -Substrate – reactants in an enzyme catalyzed reaction -Active site – spot on enzyme where substrate binds

Enzymes lower activation energy by positioning substrates in a way that is favorable to reacting *The enzyme does not provide any energy!

Cofactors and Coenzymes help enzymes function properly Cofactors = inorganic molecules such as zinc, iron, copper (“minerals”) Coenzymes = organic molecules such as vitamins

Competitive Inhibitors – a molecule binds into the active site, blocking access to the substrate Often similar in shape to the substrate (at least a portion of it)

Non-competitive Inhibitors – bind elsewhere on enzyme and forces change in shape of active site

Temperature As it increases, molecules move faster, collide more often and with more energy Enzymes have an ideal temperature which matches environment in which they are supposed to be active Too cold – molecular motion too slow Too hot – enzymes lose shape (denature)

pH Enzymes also have ideal pH ranges - based on where they are meant to be active

Substrate Concentration - as substrate concentration increases, enzyme activity increases until a maximum rate is achieved