1. Warm Up
Base your answer to this question on the diagram below, which represents stages in the digestion of a starch, and on your knowledge of biology.
The products would most likely contain
A. simple sugars. C. amino acids.
B. fats. D. minerals.

2. Enzymes: “Helper” Protein molecules

3. Chemical Reactions
A. When bonds are broken and reformed to make different substances.
EX:
Reactants Products
C6H12O6 + 6O2 6CO2 + 6H2O
Remember, energy is stored in the bonds of the compounds.
Reactants are also called raw materials – They need to know this term.
Have them tell you the reactants and products of the above equation.

4. Chemical reactions of life
Processes of life
A. building molecules = synthesis
B. breaking down molecules = digestion + +

5. What is needed to start a reaction?
Energy absorbed
Activation energy
Reactant
Products
Energy released
Activation Energy: energy required to get a reaction started
Point out the high amount of energy needed with reaction in graph.
The activation energy on the graph comes in when you click the mouse – the purpose is to get the answer from them first. – Remember enzyme demo

6. Nothing works without enzymes!
How important are enzymes?
A. all chemical reactions in living organisms require enzymes to work
building molecules = synthesis enzymes
breaking down molecules = digestive enzymes +
enzyme
We can’t live without enzymes! +
enzyme

7. B. enzymes speed up reactions = catalysts

8. C. Digestion Reaction
Is the breakdown of a complex molecule into simpler substances
These reactions RELEASE energy
Enzyme
Enzyme
Enzyme
Enzyme

9. D. Synthesis Reaction
The combining of simple molecules into a more complex ones
This reaction builds new molecules and/or STORES energy
Reactants
Products
Enzyme
Enzyme
Enzyme

10. Examples
Synthesis
enzyme +
Digestion
enzyme +

11. Enzymes are proteins & each enzyme is the specific helper to a specific reaction.
A. Each enzyme needs to be the right shape for the job
B. Enzymes are named for the reaction they help
i. sucrase breaks down sucrose
ii. proteases breakdown proteins
iii. lipases breakdown lipids
iv. DNA polymerase builds DNA
Oh, I get it!
They end in -ase

12. Enzymes aren’t used up **Enzymes are NOT changed by the reaction
A. used only temporarily
B. re-used again for the same reaction with other molecules
C. very little enzyme needed to help in many reactions
substrate
product
active site
enzyme

13. It’s shape that matters!
Lock & Key Theory
A. shape of protein allows enzyme & substrate to fit
B. specific enzyme for each specific reaction
Substrate
Enzyme
Products

14. What Affects Enzyme Activity
Temperature:
pH:
Temperature: all enzymes have an optimal temp they work best at
pH: acidity/alkalinity can increase or decrease the function of an enzyme
Concentration: Increasing the concentration of the enzyme can increase the rate of the chemical reaction 3 7 5 9 11 13
Neutral
Battery Acid
Bleach
Blood (7.5)

15. Temperature & Effect on Rates of Enzyme Activity
A. Optimum (best) temperature
i. greatest number of collisions between enzyme & substrate
ii. human enzymes = 35°- 40°C (body temp = 37°C)
B. Raise temperature (boiling)
i. denature protein = unfold = lose shape
C. Lower temperature
i. molecules move slower
ii. fewer collisions between enzyme & substrate

16. Temperature human enzymes Reaction Rate Temperature ( ̊ C) 37°
What’s happening here?!
37°
Reaction Rate
Temperature ( ̊ C)

17. pH & Effect on Rates of Enzyme Activity
A. changes in pH = changes protein shape
B. most human enzymes work best at pH 6-8
i. depends on where in body
ii. pepsin (stomach) = pH 3
iii. trypsin (small intestines) = pH 8

18. pH stomach pepsin intestines trypsin reaction rate pH 1 2 3 4 5 6 7 8
What’s happening here?!
reaction rate 1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH

19. Denature
A. When enzymes are exposed to extreme pH or high temperatures, they can denature
B. When denatured, an enzyme will no longer function, due to a change in enzyme structure
C. This is why running high fevers for extended time is cause for concern

20. Enzyme vocabulary review
Protein; speeds up chemical reactions by lowering activation energy
Substrate
molecule that enzymes work on
Products
what the enzyme helps produce from the reaction
Active site
part of enzyme that substrate molecule fits into