Chemical Reactions and Enzymes

Learning Targets “I Can…” Explain how chemical reactions affect bonds. Describe how energy changes affect how easily a chemical reaction will occur. Explain why enzymes are important to living things.

Chemical Reactions Chemical reactions can either release energy or absorb energy. REACTANTS: The chemicals that enter the reaction PRODUCTS: The chemicals produced by the reaction 2 H 2 O 2  2 H 2 O + O 2 REACTANT: Hydrogen Peroxide PRODUCTS: Water and Oxygen

Energy-Releasing Reactions (Exothermic)

Energy-Absorbing Reaction (Endothermic)

Chemical Reactions Chemical reactions usually require energy to get started; this energy is called the ACTIVATION ENERGY. Enzymes help reactions start by lowering the activation energy. Enzymes essentially make it easier for two reactants to find each other (in an endothermic reaction) OR they assist in the breaking of chemical bonds within a reactant ( in an exothermic reaction.)

Energy-Releasing Reactions (Exothermic) H2O2H2O2 H 2 O + O 2 “SUBSTRATE”

What about other enzymes? Meet Phosphofructokinase (PFK)!

What about other enzymes? PKF is an enzyme that speeds up the chemical reaction to break down sugars from your food into energy, ATP. The chemical reaction requires energy and is one step during cellular respiration.

What about other enzymes? PFK is regulated according to how much sugar is in your body. If you need to break down more sugar for energy, then your body activates more PFK. If you have plenty of energy, then your body inactivates PFK and stores the sugar for later use.

VLabVLab: Enzymes Learning Targets “I Can..” Investigate how changes in pH, temperature, substrate concentration, and regulators affect an enzyme and its activity.

VLabVLab: Enzymes The simulation will show the effectiveness of the enzyme, PFK, by measuring how fast it converts reactants to products. The reaction rate (velocity) will be expressed as millimoles of product formation per minute (mmol/min).

References ple_ocr_21c/further_chemistry/energy_changes_chem istry/revision/3/ ple_ocr_21c/further_chemistry/energy_changes_chem istry/revision/3/ ncepts%20Animations%20and%20videos/chapter5/vid eos_animations/catalase.html ncepts%20Animations%20and%20videos/chapter5/vid eos_animations/catalase.html ch?id=1 ch?id=1 mediaviewer/File:Phosphofructokinase_6PFK_wpmp.p ng mediaviewer/File:Phosphofructokinase_6PFK_wpmp.p ng