2. Opener: Wednesday, 9/28 Compare & contrast these molecules--# bonds, elements, etc.: Carbohydrates Protein Lipid

3. 2.4 KEY CONCEPT Life depends on chemical reactions!

4. Oh Snap! Remember this from PHY SCI??? Mg + 2H 2 O --> Mg(OH) 2 + H 2Mg + 2H 2 O --> Mg(OH) 2 + H 2 Reactants Products Reactants Products Mg + 2H 2 O --> Mg(OH) 2 + H 2Mg + 2H 2 O --> Mg(OH) 2 + H 2 Coefficients Subscripts Coefficients Subscripts

5. Bonds break & form during chemical reactions! -allows organisms to grow, develop, reproduce, and adapt. -breaks down some substances & forms others Reactants Yields (Makes) Products

6. CO 2 + H 2 O H 2 CO 3 Bond energy = amount of energy that breaks a bond!Bond energy = amount of energy that breaks a bond! Equilibrium = when reactants and products form at the same rate.Equilibrium = when reactants and products form at the same rate.

7. Activation energy!!! amount of energy needed for a particular chemical reaction to occur!! Activation Energy:

8. Exothermic reactions release more energy than they absorb! –Reactants higher bond energies than products –Excess energy is RELEASED by reaction.

9. Endothermic reactions absorb more energy than they release! –Reactants- lower bond energies than products –Energy ABSORBED by reaction

10. Energy (absorbed or released) can be in the form of: -heat-light

11. pH is important…why? measures acidity of solutionmeasures acidity of solution Normal limits: narrow range!Normal limits: narrow range! Buffers: regulate pH (blood, seawater)Buffers: regulate pH (blood, seawater) Small change = BIG DEAL!!!!Small change = BIG DEAL!!!! 4 -5 on pH scale 4 -5 on pH scale  10x more acidic!! OUCH!!

12. Pineapple Enzyme Lab Set up today Results tomorrow Test FRIDAY!!

13. Happy Thursday! 9/29 Test Friday!Test Friday! Please listPlease list THREE questions that you haveTHREE questions that you have TWO things you’re sure aboutTWO things you’re sure about ONE thing you want to know about ENERGY that we didn’t learn!ONE thing you want to know about ENERGY that we didn’t learn!

14. 2.5 KEY CONCEPT Enzymes are catalysts for chemical reactions in living things!

15. Catalyst (speeds up rxn rate) 1. Lowers Act. En., speeds up reaction rate 2. Not used up (reused over & over)

16. Enzymes: - Proteins = biological catalysts -Help many chemical rxns -(live, reproduce, grow) (digestion, respiration, reproduction, movement & cell regulation)

17. Enzyme structure & function -Each particular enzyme can catalyze only one chemical reaction!!!

18. Structure can be altered by: - temperature - pH “Optimal” Temp, “Optimal” pH If Out of range  broken down, messed up…“Denatured” High fever = dangerous, enzymes in body can’t function at high temps!!! Enzyme Structure Can Be Altered by:

19. Homeostasis & Enzymes! -Function best w/in small range of conditions. –Changes in temp & pH can break H bonds! –Function depends on its structure...so…

20. Structure allows only certain things to bind!!! –Substrates = specific reactants enzymes act on! Ex. Amylase (enzyme) only works on starch (substrate) –Active site – where substrate binds to enzyme substrates (reactants) enzyme Substrates bind to an enzyme at certain places called active sites.

21. The lock-and-key model: illustrates how enzymes function! –substrates brought together –bonds break/form –Product is made, released from enzyme –Enzyme is REUSED

22. Let’s DRAW IT! Lock:Key: Substrates bind to an enzyme at certain places called active sites. The enzyme brings substrates together and weakens their bonds. The catalyzed reaction forms a product that is released from the enzyme.

23. New food recommendations— not a pyramid! http://www.choosemyplate.gov/

24. Pineapple Enzyme Lab Results Test TOMORROW!! Go over Ch 4 Quiz afterGo over Ch 4 Quiz afterlab