1. ENZYMES

3. What’s an Enzyme?
Enzymes are proteins.
Enzymes are catalysts.
Catalysts speed up chemical reactions
End in –ase (Ex: sucrase, catalase)
Without an enzyme!
With an enzyme!

4. WARNING Superman had Kryptonite Enzymes have Acids (pH)
Cold Temperatures
Extreme Hot Temps
slow down the
enzyme and the
chem. reaction

5. How do you speed up enzymes?
Add more of the enzyme.
Warm up the enzyme! Don’t warm it too much or something may happen

6. Chemical Reactions
Reactants → (yield) Products
Ex: Fe + O2 → rust

7. TYPES OF Chemical Reactions
1. Condensation (dehydration synthesis)
means….. You pull out water to produce one single molecule from the original two molecules.
Molecule + Molecule  One Larger Molecule + Water
2. Hydrolysis
means……. To use water to break one molecule into two smaller molecules.
One Larger Molecule + Water  Molecule + Molecule

8. Dehydration or hydrolysis?

9. Why do we need Enzymes?
Speed up rate of chemical reaction by lowering the activation energy (energy needed to start chemical reaction)
Without enzyme
Activation energy
without enzyme
Activation
Energy with enzyme
Reactants
With enzyme
Products

10. How do ENZYMES work? The enzyme attaches to reactants
The reactants that bind to the enzyme are known as the substrates.
The part of the enzyme where the substrate attaches to the enzyme is called the active site.
The shape of the active site only fits the shape of the substrate, like a lock fits a key. Only the correct substrate binds to the enzyme.

11. Lock-and-Key Mechanism- Enzymes can only bind to certain substrates
Reactants/
Substrates
Enzyme
Lock-and-Key Mechanism- Enzymes can only bind to certain substrates

12. Once the enzyme and substrate are together, the enzyme holds the substrate so the reaction can occur. Once the reaction is over, the enzyme unlocks the product and the enzyme can start a new reaction with an identical substrate.
Enzymes are not permanently changed or used up in reactions

13. A change in the pH of the enzyme can cause a change in the shape of the active site, therefore changing the activity of the enzyme.

14. Sucrase

15. Reactions can absorb energy OR release energy ENDERGONIC Reactions
Figure 2-19 Chemical Reactions
Reactions can absorb energy OR release energy
Section 2-4
ENDERGONIC Reactions
EXERGONIC Reactions
Energy-Absorbing Reaction
Energy-Releasing Reaction
Products
Activation
energy
Activation energy
Reactants
Reactants
Products
Go to Section:

16. Effect of Enzymes Reaction pathway without enzyme Activation energy
Reactants
Activation
energy
with enzyme
Reaction pathway
with enzyme
Products
Go to Section:

17. Factors that affect Enzyme Function
Temperature pH
Enzyme concentration
Substrate concentration
Salinity
Activators
Inhibitors
catalase

18. Factors Affecting Enzyme Activity
TEMPERATURE- the average kinetic energy a substance. Too much energy can cause an enzyme to unravel. If an enzyme unravels it is said to have DENATURED. Once an enzyme denatures it can’t be put back together again
Not enough energy means that substrates don’t “bump” into the active site of the enzyme for the reaction to occur.

19. How would enzyme activity differ in endotherms vs ecotherms?

20. Factors Affecting Enzyme Activity
pH- is the concentration of H+ ions in a solution
H + ions interfere with bonds that hold the enzyme in it correct shape. More H+ (lower pH) means the enzyme with DENATURE.

21. Can you explain what is happening after every meal?
pepsin
trypsin
pepsin
reaction rate
trypsin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH

22. Factors affecting Enzyme Activity
Substrate concentration
As  substrate =  reaction rate
more substrate = more frequently collide with enzyme
Reaction rate levels off
all enzymes have active site engaged
enzyme is saturated
maximum rate of reaction
Why is it a good adaptation to organize the cell in organelles?
Sequester enzymes with their substrates!
substrate concentration
reaction rate

23. Factors affecting enzyme function
Enzyme concentration
As  enzyme =  reaction rate
more enzymes = more frequently collide with substrate
Reaction rate levels off
substrate becomes limiting factor
not all enzyme molecules can find substrate
Why is it a good adaptation to organize the cell in organelles?
Sequester enzymes with their substrates!
enzyme concentration
reaction rate