Chemical Reactions & Enzymes

I. Chemistry A. We already know that all living things are made up of chemical compounds. B. Chemistry is not only what life is made up of- chemistry is also what life does. 1. growth, interaction with environment, reproduction & movement are all based on chemical reactions

II. Chemical Reactions A. Chemical reactions: is a process that changes, or transforms one set of chemicals into another by changing bonds between atoms 1. Can occur quickly or slowly B. Chemical reactions have two parts: 1. Reactants: elements or compounds that enter the reaction (what you start with) 2. Products: elements or compounds that are produced (what you end up with)

II. Chemical Reactions Examples 2H₂ + O₂  2H₂O _______ _______ _______ _______ C₆H₁₂O₆ + 6O₂  6CO₂ + 6H₂O __________ __________

III. Energy in Reactions A. Whenever chemical bonds form or are broken energy is released or absorbed. Think about after you ingest a meal B. Energy changes is a good indicator if a chemical reaction will occur. C. Chemical reactions that release energy (exothermic)often occur spontaneously D. Chemical reactions that absorb energy (endothermic) will not occur without a source of energy

III. Energy in Reactions Examples Reactions that release energy Pure Sodium + Water Reactions the absorb energy (Take the energy of stirring) Cold Packs

IV. Activation Energy A. The energy needed for a chemical reaction to start is known as activation energy. B. Examples

V. Enzymes A. Some chemical reactions that make life possible are too slow or have very high activation energies therefore our cells compensate by making catalysts B. Catalysts are substances that speed up reactions by lowering the activation energy. C. Enzymes are proteins that act as catalyst inside a cell.

V. Enzyme Action First in order for any reaction to occur enough energy must be present among the reactants so bonds can break and new bonds can form. A. Enzyme-Substrate Complex: enzymes provide a site where reactants can be brought together and react 1. Reactants that fit into the enzyme are known as substrates 2. The substrates bind to an area on the enzyme that is known as the active site

VI. Regulation of Enzyme Activity A. All Enzymes: 1. Fit one specific type of substrate (think lock and key) 2. Work best around normal human body temperature 3. Can be influenced by a change in pH 4. Increase activity with increasing amounts of substrate