MA Biochemistry 1.3 Enzymes are catalysts for biochemical reactions and are affected by a variety of factors.

*two page notebook format*  Page 20  Do Now:  Why is water important to life?  How are hydrogen bonds similar to ionic bonds?  What factors influence the rate of chemical reactions?  Page 21  Monday, October 20, 2014  Topic: Biochemistry  Objectives: Connect properties of water to enzyme activity.  Visualize the impact of H+ concentration on enzyme activity.  Analyze the “lock and key” model of enzyme action.

Remember hydrogen bonding…  And the properties of water that go along with hydrogen bonding…

Properties related to hydrogen bonds High specific heat – water resists changes in temperature Cohesion – water molecules stick together Adhesion – water sticks to other substances

Many compounds dissolve in water The solvent is present in greater concentration. It dissolves the solute. (example is water, can include oils) The solute is the substance that dissolves. (examples are salt, sugar, proteins) Many substances dissolve in water because it is polar – so ionic or charged molecules dissolve easily in it.

Some compounds form acids or bases ACIDS release protons (hydrogen ions – H+) in water BASES remove H+ ions from water pH is the scale that measures H+ concentration BUFFERS help maintain pH and resist change

Remember… What is a chemical reaction?

Enzymes are catalysts for chemical reactions  Energy equal to the bond energy in the reactants = activation energy required to initiate a chemical reaction  Enzymes lower activation energy.  Enzymes control the rate of reactions.  Sketch figure 5.1 (pg 52) in your notes.

Enzymes allow chemical reactions to occur under tightly controlled conditions  Enzymes make reactions happen at the correct time and place, at the correct speed, to meet the needs of life.  Most enzymes are proteins.  Enzymes take part in almost every process that happens inside living beings.  Enzymes work best at the correct temperature and pH. The wrong temperature or pH can denature proteins – and enzymes are proteins.

Enzymes are specific  Enzymes have a precise shape, and they act on specific substrates – the reactants they bind to and work on.  Sketch the enzyme and substrates shown on p 54 into your notes.  Analyze: read p 54 and analyze the “lock and key” model for enzyme action. What is accurate about the model? What is not quite correct?

2.5 Formative Assessment  Answer 1-4 on page 54. Write on the left side of your notebook.  Homework:  Question 5: Organisms need to maintain homeostasis, or stable internal conditions. Why is homeostasis important for the function of enzymes.  Summary: Bottom of right side of notebook. 3-5 sentences about what you learned today.