Honors Enzymes and Biochemical Reactions Notes PDF

HONORS  Metabolism Metabolism = all of the chemical reactions within each cell of an organism. – Provide energy for life’s processes – Create key molecules Chemical reactions = the breaking and forming of bonds between different substances during chemical changes...

HONORS  Metabolism Metabolism = all of the chemical reactions within each cell of an organism. – Provide energy for life’s processes – Create key molecules Chemical reactions = the breaking and forming of bonds between different substances during chemical changes. Overall, reactions absorb or release energy. – Breaking a bond requires energy to be absorbed. – Forming a bond allows energy to be released. Due to the law of conservation of energy, no energy in the system is lost  it just changes forms. – May be released as heat, light, etc.  Metabolism Biochemical reactions are either… – Catabolic: break down larger molecules into simpler compounds  a release in energy = exergonic – Anabolic: build larger molecules from smaller ones  requires consuming energy to do it = endergonic All reactions require energy to happen. – Activation energy = the amount of energy needed to make a chemical reaction start  Chemical Reactions Reactants (substrate): substances that are changed during a chemical reaction Products: substances that are made by a chemical reaction reactants products  Types of Reactions Endothermic: absorbs energy (in the form of heat or light) – Ex. Photosynthesis Exothermic: releases energy (in the form of heat or light) – Ex. Cellular Respiration EXOTHERMIC ENDOTHERMIC Less energy in products than reactants More energy in products than reactants Key Biochemical Reactions 6CO2 + 6H2O  C6H12O6 + 6O2 Photosynthesis Light energy is stored as chemical energy in sugar, therefore it is an ENDOTHERMIC reaction. C6H12O6 + 6O2  6CO2 + 6H2O Cellular Respiration Chemical energy in sugar is converted to chemical energy released as ATP, therefore it is an EXOTHERMIC reaction.  Enzymes Metabolic reactions are controlled by enzymes. – Enzymes: mostly proteins that speed up biochemical reactions by lowering the activation energy. – Because they speed up reactions, they are called catalysts = substances that speed up reactions without being permanently altered  Enzymes Enzymes are very specialized molecules that bind to reactants (aka, substrate) and help to break or form bonds  releasing a newly created product. Enzymes are not changed in a reaction and can be used over and over again!! They are CRITICAL for the regulation of life’s processes in all organisms!!  Enzymes Enzymes are very specific. – They have an active site that fits only one substrate (reactant). – Once substrate connects, the bind tights  an induced fit. substrate (reactant) active site enzyme  Enzymes Enzymes can break bonds in a substrate to form two products.  Enzymes Enzymes can make bonds between substrates to form one product.  Denaturation Enzyme’s active site gets deformed and loses its specific shape  loss of biological activity – Caused by environmental changes like: extreme changes in pH, temperature, ion strength, and solubility Some enzymes can be “renatured” to their original shape, but not always. Normal enzyme Denatured enzyme Ways to change the rate of a chemical reaction 1. Temperature = increasing temperature increases the rate of the reaction – Molecules are moving FASTER and colliding more with each other. 2. pH = how acidic a solution is – Most enzymes only work at very specific pH so if the pH changes it can affect speed of reaction. Ways to change the rate of a chemical reaction 3. Substrate Concentration = the higher the amount of substrate, the faster the reaction – Due to more particle collisions. 4. Catalysts = (like enzymes) speed up reactions – Lower activation energy needed for the reaction to start. 5. Competitive Inhibitor = slows down reaction – Competes with substrate for the active site on the enzyme.  https://www.youtube.com/watch?v=q gVFkRn8f10