Exploring Enzyme Function: Catalysts of Life

1. Warm-up • What are the four macromolecules and their function?

2. Mindstretcher 1. What is the name of the region at which reactants bind to an enzyme during a biochemical reaction? a) Catalyst b) Product c) Substrate d) Active site

3. Mindstretcher 2. How are enzymes able to speed up biochemical reactions? a) They provide energy to the reactants. b) They absorb energy from the products. c) They lower the activation energy of the reaction. d)They increase the number of available reactant particles.

4. Mindstretcher 3. The diagram below shows a single glucose molecule. This molecule is also referred to as a) A polysaccharide b) A monosaccharide c) A fatty acid d)A nucleic acid

5. Enzymes

6. Metabolism • The totality of an organism’s chemical processes, involving thousands of precisely coordinated, complex, efficient and integrated chemical reactions in the cell.

7. Enzymes are “biological catalysts”:they make all the chemical reactions happen in the cell!

8. Enzymes = “biological catalysts” • Catalyst = chem agent that accelerates a reaction without being permanently changed • Protein • Specific • Reusable

9. Catalyst: something that speeds up a chemical reaction Enzyme:proteins that speed up/help jump start reactions in an organism Therefore enzymes are catalystsbecause they speed up biochemical reactions • We need enzymes for every process that happensin our bodies! e.g. Digesting food, replicating DNA

10. Enzymes Substrate:the material that an enzyme binds to and breaks down Complex: enzyme and substrate together Active site: Where the enzyme and substrate bind together

11. Enzymes Enzymes often end in -ase • Lactasebreaks down lactose • Amylasebreaks down amylose • Make up your own enzyme-substrate names. Write on your paper

12. Quick Check 1. What’s a substrate? 2. What do enzymes usually end in? 3. Is catalase an enzyme or a substrate? How do you know? 4. What do you predict is the substrate for the enzyme sucrase?

13. Enzyme Specificity Enzymes are specific: • They only work with one substrate • The enzyme and the substrate fit together like a lock and a key Enzymes are reusable: meaning _________ therefore the enzyme is not changed during a reaction The substrate is changed, it becomes the product(s)

14. Activation Energy • For reaction to occur, reactants must absorb energy to break bonds • Activation Energy is the amount of energy reactant molecules must absorb to start a chemical reaction.

15. Enzymes Lower Activation Energy • Stress bonds for catabolism (breakdown) • Orient molecules for anabolism (building) • Provide microenv. that facilitates the reaction

16. Catalytic Cycle of Enzymes

17. Factors Affecting Enzyme Activity • Enzymes are proteins • Proteins are long chains of amino acids foldedinto a very specific shape • The function of every protein depends on itsstructure or shape • Change the shape of an enzyme and it won’t work • What would change the shape of an enzyme?

18. Factors Affecting Enzyme Activity • Temperature—increase temp, increase reaction rate, until heat denatures protein • pH – most optimal from 6-8 • Ionic conc. – most enz cannot tolerate high salinity • Many adaptations are exceptions to above

19. Destroying Enzymes An enzyme’s job is determined by itsSHAPE Denature: enzyme changesshapeso that it no longer works properly Enzymes are denatured by hightemperaturesand lowpHs.

20. Optimum Temperature and pH • Find the highest point on the curve. • Drop down to the x-axis. • Record temperature or pH.

21. Factors Influencing Rate of Enzyme Action: pH pH - the optimum (best) in most living things is close to 7 (neutral) • high or low pH levels usually slow enzyme activity • A few enzymes (such as gastric protease) work best at a pH of about 2.0

22. Factors Influencing Rate of Enzyme Action: Temperature Temperature - strongly influences enzyme activity • optimum temperature for maximum enzyme function is usually about 35-40 C. • reactions proceed slowly below optimal temperatures • above 45 C most enzymes are denatured (change in their shape so the enzyme active site no longer fits with the substrate and the enzyme can't function)

23. Factors Influencing Rate of Enzyme Action: Concentrations of Enzyme and Substrate • When there is a fixed amount of enzyme and an excess of substrate molecules -- the rate of reaction will increase to a point and then level off.

24. Enzymes (Notes) enzyme lactase glucose + galactose lactose + H2O substrate products

25. Enzyme Foldable SUBSTRATES A & B ENZYME-SUBSTRATE COMPLEX 1 2 ENZYME \ PRODUCT AB 3 4 ENZYME

26. TAB 1 • ENZYME: proteins that act as catalyst to speed up chemical reactions in living cells. • SUBSTRATE: the substance and enzyme acts on

27. Tab 2 Induced Fit: ACTIVE SITE: a region of an enzyme molecule which the substrate binds to • A change in the shape of an enzyme’s active site • Induced by the substrate

28. Tab 3 Factors that Affect Enzyme Action: • pH • Temperature • Amount of substrate

29. Tab 4 • Reusable or NOT reusable? Reusable • Specific or not specific? Specific • Effect on chemical bonds that join atoms in molecules: • Break bonds or • Make bonds • What macromolecule? Enzymes always protein • Examples of biological catalysts: Protease, Lactase, Amylase

30. ReviewQuiz!

31. Question 1 What are proteins that speed up chemical reactions called? A. Amino acids B. Reactants C. Enzymes D. Substrates

32. Question 2 What is a substrate? A. The compound that is before the arrow in a chemical reaction B. Another name for an enzyme C. The material that an enzyme binds to D. The term used to describe the structure formed after an enzyme binds with a complex

33. Question 3 How do enzymes affect the activation energy of a chemical reaction? A. Enzymes increase the activation energy needed for a reaction to start B. Enzymes decrease the activation energy needed for a reaction to start C. Enzymes do not alter activation energy of chemical reactions D. Enzymes initially decrease activation energy than increase it

34. Question 4 Which of the following statements best describes enzymes? A. enzymes cannot be reused after a reaction B. Enzymes are organic catalysts C. Enzymes slow down chemical reactions D. Enzymes can bind to any substrate

35. Question 5 An enzymes job is determined by its what? A. size B. shape C. color D. Activation energy

36. Answers

37. Question 1 What are proteins that speed up chemical reactions called? A. Amino acids B. Reactants C. Enzymes D. Substrates

38. Question 2 What is a substrate? A. The compound that is before the arrow in a chemical reaction B. Another name for an enzyme C. The material that an enzyme binds to D. The term used to describe the structure formed after an enzyme binds with a complex

39. Question 3 How do enzymes affect the activation energy of a chemical reaction? A. Enzymes increase the activation energy needed for a reaction to start B. Enzymes decrease the activation energy needed for a reaction to start C. Enzymes do not alter activation energy of chemical reactions D. Enzymes initially decrease activation energy than increase it

40. Question 4 Which of the following statements best describes enzymes? A. enzymes cannot be reused after a reaction B. Enzymes are organic catalysts C. Enzymes slow down chemical reactions D. Enzymes can bind to any substrate

41. Question 5 An enzymes job is determined by its what? A. size B. shape C. color D. Activation energy