Bellringer Please grab your lab manual from the front table.

Macromolecule Lab Black: Carbon White: Hydrogen Tan/Purple: Oxygen Silver: Nitrogen

Chemical Reactions and Enzymes

Learning Target Explain the basic structure of proteins and discuss the role of enzymes in chemical reactions.

Chemical Reactions   Reactant Product + Reactant + Reactant Product An interaction between 2 chemicals – chemical bonds are either broken or formed. The two parts of a chemical reaction are the REACTANTS and the PRODUCTS.  Reactant Product + Reactant + Reactant Product

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Chemical reactions & energy  Chemical reactions & energy Some chemical reactions release energy (Exothermic) digesting polymers Some chemical reactions require (Endothermic) input of energy building polymers

 Chemical Reactions Activation Energy - the energy needed for a chemical reaction to start Most reactions in our bodies require high energy to occur quickly enough to keep a cell working properly. energy released by the reaction products reactants

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ENZYMES  Enzymes are catalysts! Enzymes are proteins that do the body’s work! Enzymes speed up chemical reactions by interacting with substrates to lessen the energy needed … Most enzymes have names that end in “-ase”

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Enzymes Act On Specific Substrates  Enzymes Act On Specific Substrates Enzymes have specific shapes! A specific substrate (the reactants) will fit in the enzyme’s active site. Enzyme + Substrate: fit like a lock-and-key (called “induced fit”). 

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Enzymes Work By Lowering Activation Energy  Enzymes Work By Lowering Activation Energy Activation Energy is the energy needed to start a chemical reaction (An energy bump you must jump over to get going). Ex: pushing a rock downhill (The enzyme acts as a crowbar)

Look at the energy graph below: activation energy without enzyme with enzyme energy released by the reaction products reactants  Talk it over question: What affect does an enzyme have?

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Factors That Influence Enzyme Activity  Factors That Influence Enzyme Activity Temperature pH Salt Concentration

Effect of Temperature  Small increase in temperature increases molecular collisions, reaction rates High temperatures disrupt bonds and destroy the shape of active site

Effect of pH: Talk it over Which curve likely represents an enzyme in the stomach? Why? Which curve likely represents an enzyme in the blood? Why?

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