1. ENZYMES

2. There are thousands of reactions that occur within organisms.
These reactions would occur very slowly
or not at all without enzymes.

3. Reactions can: Build new molecules Break down molecules+
Break down molecules +
Enzymes speed up theses chemical reactions.
Enzymes are catalysts.

4. Enzymes are not changed by the reaction.
Lock & Key:
Specific substrate attaches to specific enzyme
product
substrate
active site
enzyme
Enzymes are not changed by the reaction.

5. How do enzymes speed up reactions?
Activation energy
the energy required to start a reaction
Enzymes lower the activation energy

8. Temperature pH ( acids & bases) How well an enzyme works depends on:
Enzyme are sensitive to temp and pH.

9. Temperature and Activity of Enzyme
Enzyme has
greatest activity
Human enzymes
37°
reaction rate
temperature

10. Temperature and Activity of Enzyme
Human enzymes
37°
reaction rate
temperature
Enzyme has lowest activity
Enzyme is inactive

11. Temperature and Activity of Enzyme
Human enzymes
37°
reaction rate
temperature
The activity of the enzyme decreases at temperatures
above and below the optimum temperature.

12. Temperature and Activity of Enzyme
Human enzymes
At which temperature
is the activity of the
enzyme the greatest?
37°
reaction rate
temperature

13. 100 °C
Some bacteria
thrive at extreme
temperatures.
-10 °C

14. pH Scale
Acid
Base

15. pH and Activity of Enzyme
Stomach pepsin
Intestine trypsin
Optimum pH = 3
Optimum pH = 8
reaction rate 1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH
Each enzyme works best at a specific pH.

16. The activity of the enzyme decreases at pH
Stomach pepsin
Intestine trypsin
reaction rate 1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH
The activity of the enzyme decreases at pH
above and below the optimum temperature.

17. According to the graphs above, which
enzyme is the least affected by pH?

18. The stomach is very acidic and has a pH of 2
The stomach is very acidic and has a pH of 2. Enzyme X breaks down proteins into amino acids in the stomach. According to the graphs above, which enzyme is enzyme X?

19. A B C
The stomach has a pH of 2 and the small intestine has a pH of 7. Starches are broken down in the small intestine. Which enzyme above will break down starch in the small intestine?