1. Enzymes & E a 3.3

2. Activation Energy (E a )

3. What if… …organisms used heat for E a ? not a practical source because… can disrupt or denature proteins is non-specific (would speed up all reactions)

4. Enzymes and E a

5. How is E a reduced? Enzymes… provide proper orientation of substrate(s) provide specific environments that promote catalysis put strain on substrate bonds, making them easier to break

6. Animation Activation Energy & Enzymes: http://www.sumanasinc.com/webcontent /animations/content/enzymes/enzymes. htmlhttp://www.sumanasinc.com/webcontent /animations/content/enzymes/enzymes. html

7. Food As Fuel 3.4

8. Redox Reactions electrons are lost from one atom and gained by another atom [see also 1.1, page 17] oxidation reduction

9. Redox Reactions oxidizing agent reducing agent sometimes entire atoms (with their electrons) are transferred during redox reactions

10. Redox… redox can occur because of relative loss or gain of electrons due to electronegativity differences… CH 4 + 2O 2 --> CO 2 + 2H 2 O C is effectively oxidized, O is reduced

11. Cellular Respiration glucose is oxidized combustion (oxidation) of glucose releases a large amount of thermal E in cells, oxidation of glucose occurs in a series of steps (controlled oxidation) to minimize E loss

13. Energy Carrier: NAD + NAD+ (nicotinamide adenine dinucleotide) is a coenzyme found in all living cells vitamin B 3 (niacin) derivative

14. Reduction of NAD+

15. Energy Carrier: FAD FAD (flavin adenine dinucleotide) is a coenzyme involved in respiration vitamin B 2 (riboflavin) derivative

16. Reduction of FAD