1. ExergonicVsEndergonic?

2. Endergonic: Building

3. Exergonic: Breakdown

4. Enzymes: Proteins that are used for chemical reactions (some RNA molecules) Enzymes can either break up or put together substrates Enzymes are specific – only work on certain substrates. Enzymes are biological catalysts that react on substrates Enzymes are NOT CHANGED in the reaction

5. Catalyst: A substance that causes a reaction to occur but does not itself get changed A substance that causes a reaction to occur but does not itself get changed Biological catalysts (enzymes) are found in ALL living cells Biological catalysts (enzymes) are found in ALL living cells

6. How do enzymes affect chemical reactions? Enzymes are catalysts which speed up the reaction by lowering the activation energy required, thus making it efficient for sustaining life. Enzymes are catalysts which speed up the reaction by lowering the activation energy required, thus making it efficient for sustaining life.

7. Activation Energy The energy required for a chemical reaction to start and continue on its own. The energy required for a chemical reaction to start and continue on its own. Similar to rolling a boulder downhill, it is the chemical ‘push’ that gets a chemical reaction going. (Enzymes lower the activation energy needed for chemical reactions. Less energy needed to start the reaction, can occur at lower temperatures.)

8. Liver, Potato Cells… Hydrogen Peroxide

9. Lowering the Activation Energy

10. How an enzyme works… Substrate: A substance that the catalyst (enzyme) acts on Substrate: A substance that the catalyst (enzyme) acts on Ex) Lactose = milk sugar (substrate) Ex) Lactose = milk sugar (substrate) Lactase = breaks down lactose (enzyme) Lactase = breaks down lactose (enzyme) Active Site: The specific region of the enzyme that combines with the substrate Active Site: The specific region of the enzyme that combines with the substrate

11. Liver/Potato Demo- Liver/Potato Demo- Reaction? Reaction? Enzyme? Enzyme? Multiple collisions…forever?? Multiple collisions…forever?? “Induced Fit”- stress on substrate bonds, weakens them…less AE needed “Induced Fit”- stress on substrate bonds, weakens them…less AE needed (text p 162,166) (text p 162,166)

12. Lock and Key: The lock is the enzyme and the key is the substrate. Only the correctly sized key (substrate) fits into the key hole (active site) of the lock (enzyme).

13. Factors that affect the rate of Enzyme Action:  Temperature: There is an optimum (best) temperature that each enzyme works in. Increase temperature, increase molecule movement, increase rate of the reaction.  Temperature too LOW, decrease the effect of the enzyme  Temperature too HIGH- Protein Denatures (breaks down/changes shape)- the enzyme will not work.

15. Denatured Enzyme Weakened H-bonds….Alpha/Beta… unravels

16. Enzyme Regulation: Factors that affect the rate of enzyme action A cell can regulate enzymatic activity by controlling the amount of enzyme produced

17. Allosteric Sites (Feedback Inhibition) A cell can regulate enzymatic activity by controlling the amount of enzyme produced A cell can regulate enzymatic activity by controlling the amount of enzyme produced

18. Noncompetetive vs Competetive Inhibition

20. Factors that affect the rate of Enzyme Action: TemperaturepHConcentration:  Increasing the amount of enzyme will increase the rate of reaction, but it will eventually level off- why?  For the same reason, increasing the substrate concentration will increase the rate of reaction, but it will eventually level off.

21. SEE ALL GRAPHS ON PAGE 3 of the Enzyme Packet

22. Enzyme Animation http://www.biotopics.co.uk/other/hienz. html http://www.biotopics.co.uk/other/hienz. html http://www.kscience.co.uk/animations/a nim_2.htm http://www.kscience.co.uk/animations/a nim_2.htm