CP BIOLOGY
ENZYME NOTES
CHEMICAL REACTIONS
 process that changes one set of chemicals into another set
 reactants = chemicals at beginning of reaction
 products = chemicals produce as a result of the reaction (end)
 chemical reactions involve breaking and forming of bonds
ENERGY IN REACTIONS
 energy is released or absorbed whenever chemical bonds form and break
 Energy changes o determine whether reaction will occur o reactions that release energy usually occur spontaneously o reactions that absorb energy will not occur with out a source of energy o living organisms must carry out reactions that require energy to stay alive, so they need a source of energy to carry out reactions – plants get energy from sunlight, animals from food they eat and break down
 Activation Energy o energy needed to get a reaction started o factor in whether overall chemical reaction releases energy or absorbs energy o even some reactions that release energy do not occur spontaneously
ENZYMES
 some chemical reactions necessary for life are too slow or have activation energies too high to make them practical for living tissue – require catalysts
 catalyst = substance that speeds up the rate of a chemical reaction, work by lowering the activation energy
 enzymes = proteins that are biological catalysts
 cells use enzymes to speed up chemical reactions that take place in cells
 enzymes are very specific – only one enzyme will work for a particular reaction, so its name is usually derived from the reaction it catalyzes

CP BIOLOGY, ENZYME NOTES, page 2
ENZYME ACTION
 for reaction to take place, reactants must hit each other with enough energy to break bonds and form new ones
 enzyme-substrate complex o enzymes provide site for reactants to come together to react o substrates = reactants in a enzyme-catalyzed reaction o substrates bind to location on enzyme called the active site - lock and key fit o substrates stay bound to enzyme until reaction completed, then they are released from the active site
 regulation of enzyme activity o enzymes can be affected by any variable that influences a chemical reaction o some enzymes work best a particular pH values o some affected by changes in temperature – enzymes in the human body work best at normal human body temperature (about 37 o C) o cells regulate enzyme activity by proteins that turn key enzymes “on” and “off” o enzymes essential:
 regulate chemical pathways
 making materials that cells need
 releasing energy
 transferring information