Chemical Reactions and Enzymes Why are enzymes important to living things?

Standards ● CLE – Describe how enzymes regulate chemical reactions in the body. ● Class Objectives: ● Describe how the enzyme and substrate interact to catalyze chemical reactions. ● Describe conditions that affect enzyme function.

Chemical Reactions  process that changes one set of chemicals into another set of chemicals

Chemical Reactions  always involve the breaking of bonds in reactants and the formation of new bonds in products  reactants - elements or compounds that enter into a chemical reaction  products - elements or compounds produced by a chemical reaction

Energy in Reactions  Energy is released or absorbed whenever chemical bonds form or are broken.  Chemical reactions that release energy often occur spontaneously.  Energy may be released as light, heat, and/or sound. ....

Energy in Reactions  Chemical reactions that absorb energy will not occur without a source of energy.  Every organism must have a source of energy to carry out chemical reactions

Activation Energy  energy that is needed to get a reaction started

Enzymes  catalyst - substance that speeds up the rate of a chemical reaction  works by lowering a reaction’s activation energy

Enzymes  enzymes - proteins that act as biological catalysts  very specific, generally catalyzing only one chemical reaction  part of an enzyme’s name is usually derived from the reaction it catalyzes

Enzyme Naming   The enzyme’s name is usually from the chemicals in the reaction it catalyzes.   Usually ends in -ase

Enzyme examples  DNA polymerase – links nucleotides together to make DNA  Carbonic anhydrase – speeds up the conversion of CO 2 to carbonic acid in the blood

The Enzyme-Substrate Complex  Enzymes provide a site where reactants can be brought together to react.  Such a site reduces the energy needed for reaction.  Substrates - reactants of enzyme-catalyzed reactions

Enzyme-Substrate Complex(Lock & Key Model) ● Substrate: ● Active Site: The reactant(s) of the chemical reaction. Part of the enzyme into which the substrate fits.

Induced Fit Model

Enzyme-substrate complex how enzymes work…  Enzyme  hexokinase  Substrates  Glucose  ATP  Substrates bind to active site on enzyme  lock and key  Once reaction is over, products of reaction are released and enzyme is free to start process again

Synthesis and Decomposition ● Enzymes can participate in two types of reactions: ● Synthesis: ● Decomposition: Decomposition A reaction in which two or more substrates are combined to form one product. A reaction in which one substrate is separated to form two or more products.

Regulation of Enzyme Activity  Enzymes can be affected by any variable that influences a chemical reaction  pH  temperature  certain proteins help turn enzymes “on” or “off”