1. Enzymes
Explain the role of enzymes as catalysts that lower the activation energy of biochemical reactions. Identify factors such as pH and temperature, and their effect on enzyme activity.

2. EQ: Why are the actions of an enzymes important to us?
Objective: Analyze the role of enzymes in organisms and Interpret a graph of the effect of an enzyme on the activation energy in a chemical reaction.
EQ: Why are the actions of an enzymes important to us?

3. Chemical Reactions
A chemical reaction changes the original substances (chemicals) into new, different substances includes: j
Reactants: the compounds that you begin with; substances that are changed by the reaction
On the LEFT side of a reaction equation
Products: the compounds that you end with (what the reaction produces)
On the RIGHT side of a reaction equation

4. Remember sugar…. What do they all end with?
Fructose
Sucrose
Galactose
Lactose
-OSE
What if I told you that there was a protein…..
pause for dramatic effect
…. that helped break down the sugars in your body…
dramatic effect #2
….. and they all end in –ase!!!

5. Activation Energy
the energy required for a reaction to begin

6. Catalysts A catalyst makes it easier for reactions to begin by:
decreasing activation energy
increasing the rate of reaction
Predict: how would the graph of this reaction change if a catalyst was added?

7. Adding a Catalyst

8. What are Enzymes?
Enzymes: Proteins that increase reaction rate and decrease activation energy
Enzymes are catalysts in living things
Needed for almost all processes of life to occur
Digestion, building proteins, the immune system…
Allow chemical reactions to occur faster
Enzymes are not altered during reactions so-can be reused

9. Stop and Think:
Since enzymes are proteins, what determines their function?

10. How Enzymes work
The structure of an enzyme allows only certain compounds to interact (bind) with it
Substrates= The compound that bind to the enzymes (reactants)
Active site = where the Substrates binds to the enzyme, where the reaction occurs
Product = what is created by the reaction
substrates (reactants)
enzyme
Active site

11. How Enzymes work: Lock-and-Key Model
Lock–and-key: Substrates fit the activation site on the enzyme the way a key fits into a lock
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.

12. You’re PERFECT!! In other words…
Enzymes are like you and your one true love: no one else fits quite like the two of you ;)
You’re PERFECT!!

13. How do enzymes work?
Enzymes often only work within a narrow range of conditions
weaken the bonds of the substrate and create new products
Since enzymes are Proteins, they depend on the correct shape.
If conditions change, it will denature the enzymes
Denature= unfold or change the shape of the enzyme
enzyme
enzyme

14. Since enzymes are protein, if you change the shape what will also change?
The function!

15. What factors affect the rate at which an enzyme works?
Temperature pH
Concentration

16. Temperature and Enzymes
Rate of reactions is affected by temperature
At low temperatures enzyme controlled reactions go slowly because the molecules have low kinetic energy.

17. Temperature and Enzymes
Rate of reaction increases as temperature increases because molecules have more energy
Optimal Temperature is the temperature at which the reaction is the fastest

18. Temperature and Enzymes
Temperatures higher than the optimal temperature will denature the enzyme The enzyme changes shape and the active site no longer matches the shape of the substrate molecule

19. Temperature and Enzymes
Draw graph in notes
Optimum temperature
Enzyme
is denaturing
Enzymes gain energy
Rate Of
Reaction
Temperature/oC

20. Girl, your so hot you denature my proteins

21. pH and Enzymes Enzymes prefer to work at an optimum pH.
Draw graph in notes
Enzymes prefer to work at an optimum pH.
Outside of its pH range the enzyme is denatured.
Optimum pH
pepsin
amylase
Rate Of
Reaction pH

22. Enzyme concentration
Draw graph in notes
The concentration of enzymes increases the rate of reaction increases.
Enzymes become saturated when the substrate concentration is high

23. Check for Understanding
As food travels through the digestive system, it is exposed to a variety of pH levels. The stomach has a pH of 2 due to the presence of hydrochloride acid (HCl), and the small intestine has a pH ranging from 7 to 9. HCl converts pepsinogen into pepsin, an enzyme that digests proteins in the stomach. Which of the following most likely happens to pepsin as it enters the small intestine?
A. It begins to replicate
B. It becomes inactive.
C. It's shape changes to engulf large proteins.
D. It's activity increases to digest more proteins.

24. Check for understanding
In living cells, enzymes act as catalysts, which may reduce the amount of activation energy required for a chemical reaction to occur.  In the graphs below, pathway x is a solid line representing the uncatalyzed reaction. The dotted line shows the catalyzed reaction. Which graph best illustrates the changes in a reaction when the catalyst reduces the amount of energy required?

25. Enzyme Graphing
Using your data form the lab, graph the effects of Temp, pH, and concentration
C – reading, level 0; graphing, level 2
H- Ask 3 before me, raise silent hand to get me
A- Complete enzyme graphing activity
M- remain in assigned table seat
P- work with your group mates, not everyone in the room, and glue to left side of notebook
SUCCESS!

26. EXIT TICKET!
Clear your desk!