ENZYMES

Chemical Reactions A process that changes a set of chemicals into another set of chemicals Ex: carbon dioxide carried in the blood must first be converted to carbonic acid Reactants = the set of chemicals that enters into a chemical reaction Products = the set of chemicals produced by a chemical reaction Chemical reactions break bonds in the reactants and form new bonds in the products

Energy When chemical bonds break or form, energy is released or absorbed Chemical reactions that release energy often occur spontaneously (EXOTHERMIC). Exo-exit or leave Chemical reactions that absorb energy will not occur without a source of energy (ENDOTHERMIC). Endo=enter Organisms need to carry out reactions that require energy Plant get energy from sunlight Animals get energy from plants or other animals and release energy by breaking down food

Energy Changes (KNOW THESE GRAPHS!!) If the reactants have less energy than the products, energy is absorbed in the reaction If the reactants have more energy than the products, energy is released in the reaction

DRAW & Label THIS!!!

DRAW & Label THIS!!

Activation Energy The energy needed to start a reaction Energy Absorbed Energy Released

THIS WILL BE ON THE TEST! Energy-Absorbing Reaction Section 2-4 Energy-Absorbing Reaction Energy-Releasing Reaction Products Activation energy Activation energy Reactants Reactants Products Go to Section:

Catalysts A catalyst is a substance that speeds up the rate of a chemical reaction by lowering the activation energy. Enzymes are proteins that act as biological catalysts to speed up chemical reactions in cells. Enzymes are very specific and they are usually named after the reaction they catalyze and end in -ase

make sure you understand these concepts 2-4 Effect of Enzymes make sure you understand these concepts 2-4 Reaction pathway without enzyme Activation energy without enzyme Reactants Activation energy with enzyme Reaction pathway with enzyme Products Go to Section:

Enzyme Action Reactants must collide with enough energy to break bonds and form new ones Enzymes provide a site for the substrates (reactants) to react, reducing the energy needed for the reaction to occur Enzymes are specific having an active site that is complementary to the shape of the substrates it catalyzes = “lock and key” This forms an enzyme-substrate complex

Regulating Enzymes Enzymes activity can be affected by any variable that influences a chemical reaction pH Temperature Ionic conditions

EFFECT OF TEMPERATURE ON ENZYME ACTIVITY

Click on the link to watch the animation http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html

FITS LIKE A PUZZLE or ‘lock and key”

Cells have proteins that can turn enzymes “on” or “off” Enzymes are important in regulating chemical pathways, making materials cells need, releasing energy, and transferring information