Chemical Reactions & Enzymes

Target #39- I can describe a chemical reaction, and it’s components Chemical reactions: changes a substance into a different substance by breaking and forming chemical bonds  Reactants: the substances being changed during a reaction  Products: the substances being made by a reaction All chemical reactions involve changes in energy  Bond energy: the amount of energy needed to break a bond between two atoms  Energy is released when bonds form  When the bond is broken, requires the same amount of energy as when made

WHAT IS AN ENZYME? Bellwork

WHAT HAPPENS TO ENERGY WHEN A BOND IS BROKEN? WHEN A BOND IS FORMED? Checking for Understanding

Target #40- I can define activation energy Target #41- I can describe a catalyst and how it relates to activation energy Some energy must be absorbed by the reactants in any chemical reaction  Activation Energy: the amount of energy that needs to be absorbed for a chemical reaction to start Catalyst: a substance that decreases the activation energy needed to start a chemical reaction

Target #42- I can describe enzymes Target #43 I can explain how enzymes affect the activation energy Chemical reactions in organisms need to take place very quickly  Enzyme: catalysts for chemical reactions in living things  Lowers the activation energy needed for chemical reactions in organisms  Involved in almost every process in organisms  breaking down food, building proteins, etc.  Enzymes are globular proteins

HOW DO ENZYMES AFFECT THE ACTIVATION ENERGY OF A REACTION? Checking for Understanding

Target #44- I can explain why enzyme structure is important Enzymes depend upon their structure for their function  Enzyme structure is important because each enzyme’s shape allows only certain reactants to bind to the enzyme

Target #45- I can define an active site Target #46- I can describe a substrate Active Site: the surface depressions where the enzyme and substrate connects Substrate: the molecule on which the enzyme acts  Has to fit into the active site of the enzyme  Temporarily bind to enzymes at specific places called activate sites  Like a lock-and-key

WHERE IS THE SUBSTRATE? THE ENZYME? THE ACTIVE SITE? Checking for Understanding

Target #47- I can use the lock and key model to explain how enzymes work Lock-and-Key Model  Substrates exactly fit the active siet of their corresponding enzyme  Enzymes bring substrate molecules close together  Enzymes decrease the activation energy needed and a chemical reaction can occur

Target #48- I can list the three factors that affect enzyme activity Changes in Temperature  Optimum temperature is normal body temp.  Lower temperatures  Bonds that determine enzyme shape are not flexible enough Prevents induced-fit  Higher temperatures  Bonds are too weak to hold the enzyme’s peptide chains in place Changes in pH  Optimum pH is between 6 and 8  Peptide bonds in parts of enzymes hold amino acids together  Sensitive to acidic environments

Target #49- I can identify on a graph when an enzyme is used in a chemical reaction