Biology Chapter 2

1. Biology Chapter 2 Chemistry In Biology

2. KEY CONCEPTEnzymes are catalysts for chemical reactions in living things.

3. Objectives for section 2-5 • Explain the effects of a catalyst on activation energy. • Elaborate on how enzymes allow chemical reactions to occur.

4. A catalyst lowers activation energy. • Catalysts are substances that speed up chemical reactions. • decrease activation energy • increase reaction rate (speeds it up)

6. Enzymes allow chemical reactions to occur under tightly controlled conditions. • Enzymes are catalysts in living things. • Enzymes are needed for almost all processes. (breakdown of glucose) • Most enzymes are proteins.

7. Enzymes allow chemical reactions to occur under tightly controlled conditions. • Enzymes do NOT increase how much product is made • Enzymes do NOT get used up in reaction • Lock-and-key model helps illustrate how enzymes function.

8. An enzyme’s structure allows only certain reactants to bind to the enzyme. • Substrates (reactants) bind to enzyme • Active site: specific location where a substrate binds on an enzyme See also page 58

9. Enzymes either form new bonds or break original bonds (enzyme lab) Lactose glucose galactose LactASE LactASE

10. Disruptions in homeostasis can prevent enzymes from functioning. • Enzymes function best in a small range of conditions. • An enzyme’s function depends on its structure.

11. Changes in temperature and pH can break hydrogen bonds. Making enzyme useless!!

12. In conclusion, chemical rxns would not occur quickly enough to sustain life without enzymes!!

13. Quick Quiz Time! • Each question will be worth 2 points • You may NOT talk and/or communicate with a classmate • Scores will be collected and recorded at the end of the chapter

14. 13. Which phrase best describes the effect of a catalyst on a chemical reaction? • Increases the temperature • Increases the volume of reactants • Decreases the reaction rate • Decreases the activation energy

15. 14. The specific reactants that an enzyme acts on are called • Catalysts • Proteins • Substrates • Active sites

16. 15. Changes in temperature and pH can decrease an enzyme’s activity by breaking • Hydrogen bonds • Peptide bonds • Amino acids • Ionic bonds

17. Trade your paper with a non-lab partner

18. 13. Which phrase best describes the effect of a catalyst on a chemical reaction? • Increases the temperature • Increases the volume of reactants • Decreases the reaction rate • Decreases the activation energy

19. 14. The specific reactants that an enzyme acts on are called • Catalysts • Proteins • Substrates • Active sites

20. 15. Changes in temperature and pH can decrease an enzyme’s activity by breaking • Hydrogen bonds • Peptide bonds • Amino acids • Ionic bonds

21. End of Show