AIM: How do enzymes aid chemical reactions? DO NOW:DO NOW: What happens during a chemical reaction? Consider the reaction: AB + CD --> AC + BD. What are the reactants? The products? VOCABULARY: chemical reaction, enzyme, activation energy, catalyst, substrate, inducedVOCABULARY: chemical reaction, enzyme, activation energy, catalyst, substrate, induced Go over HW pg 43 questions 1, 2, 4Go over HW pg 43 questions 1, 2, 4 Science Fair topic due Monday via Science Fair topic due Monday via Pg 53 questions 1-5 due TuesdayPg 53 questions 1-5 due Tuesday Test Wednesday Chapter 2 Sections 1, 2, AND 4 ONLY!Test Wednesday Chapter 2 Sections 1, 2, AND 4 ONLY!

Homework Review Use the structure of a water molecule to explain why it is polar. –The oxygen molecule has a greater attraction for the electrons. Therefore, the oxygen end of the molecule is slightly negative, while the hydrogen ends are slightly positive. Compare acidic and basic solutions. –Acidic solutions contain more H+ ions than OH- ions. Basic solutions contain more OH- than H+. Acids taste sour, while bases taste bitter. What does pH measure? –pH measures the concentration of H+ in a solution.

Review of Do Now What happens during a chemical reaction? –Bonds are broken and re-formed. Consider the reaction: AB + CD --> AC + BD What are the reactants? The products? –Reactants: AB, CD –Products: AC, BD

Collision Theory: Mrs. D’Anna vs. Mike Tyson for the (sort of) heavyweight championship of the world! In order for a chemical reaction to take place, the reactants must collide with sufficient energy and in the proper orientation. The initial energy required to get a chemical reaction started is called the activation energy.

What energy changes take place during a chemical reaction? Is this reaction endothermic or exothermic? Explain. What do you think is represented by the following labeled parts of the graph: Reactants Products EA “delta” G

Closing Question Sketch an energy diagram for the reverse chemical reaction. Should this reaction be exothermic or endothermic?

Is this reaction endothermic or exothermic? How do you know?

Summary… Chemical reactions occur when bonds between molecules are broken and reformed.Chemical reactions occur when bonds between molecules are broken and reformed. An exothermic reaction releases energy (heat) An exothermic reaction releases energy (heat) An endothermic reaction absorbs energy (heat)An endothermic reaction absorbs energy (heat)

What are some factors that effect enzyme activity? Do Now: What takes place in a chemical reaction? What is the difference between exothermic and endothermic?Do Now: What takes place in a chemical reaction? What is the difference between exothermic and endothermic? VOCABULARY: chemical reaction, enzyme, activation energy, catalyst, substrate, inducedVOCABULARY: chemical reaction, enzyme, activation energy, catalyst, substrate, induced Science Fair topic due Monday via Science Fair topic due Monday via Pg 53 questions 1-5 due TuesdayPg 53 questions 1-5 due Tuesday Test Wednesday Chapter 2 sections 1, 2, 4 ONLY!Test Wednesday Chapter 2 sections 1, 2, 4 ONLY!

What do you already know about enzymes? (2 min) What type of molecule is an enzyme? What do enzymes do? How do they work?

Characteristics of Enzymes Proteins Substrate Specific (lock and key) Induced fit (handshake) Biological catalysts Not consumed by a reaction

Induced Fit with Substrate

An Induced Fit AB

How do enzymes act as biological catalysts? How is the red curve (enzyme added) different from the black curve (no enzyme added)?

Activity Page 51 Analyzing Data Read the passage and study the graph. Answer questions 1-6 in groups.

Closing Thought What is the effect of pH on enzyme activity? Why do you think this occurs?

Effect of Temperature and pH on Enzyme Activity