Learning Target: Enzymes in Action

Learning Target #1: Enzymes I Can… Describe the general role of enzymes in metabolic cell processes. I Will… Describe the components of metabolic chemical reactions. Describe the general characteristics of enzymes including factors that affect how enzymes work.

Enzymes are the Super Heroes of Homeostasis! KEY IDEA: Life depends on chemical reactions Metabolism –  All the chemical reactions that take place in your body and cells.  Anabolism – joining materials together  Catabolism – breaking materials apart Why?

Reactants Yield sign Reactants – substances changed during a chemical reaction (Rxn). Products – substances made during a chemical Rxn. Chemical bonds are broken and formed. Bond energy – energy required to break a bond between two atoms. Products

Activation energy – energy that must be absorbed by the reactants before the chemical Rxn can take place.

Endothermic Rxn – Overall net energy is absorbed. Reactants have low bond energy. Products have high bond energy. More energy must go into the reaction and is stored in the bonds of the products.

Exothermic Rxn – Overall net energy is released. Reactants have high bond energy. Products have low bond energy. Excess energy goes out of the reaction while little is stored in the bonds of the products

Enzymes – catalyst for living things. Catalyst  Lowers activation energy  Is NOT a reactant or a product  Is NOT used up or changed in the reaction Catalyst Reactants Products Lowers activation energy needed Increases Rxn rate

Enzymes are specific: Lock-and-Key Model Substrates/reactants bind to enzyme at active sites (binding sites on enzyme). Enzyme acts on substrate(s) and weakens bonds (bond energy) Less activation energy needed. The catalyzed reaction forms a product released from the enzyme.

Denaturing Enzymes Almost all enzymes are proteins (polypeptide chain) Shape / folding is maintained by hydrogen bonds Temperature and pH greatly affect enzymes Temperatures just slightly above normal body temp will break the hydrogen bonds

Substrate Enzyme Ratio Not enough enzyme Optimal Too much enzyme