1. Section 2.4 &2.5: Enzymes

2. To the penny placed on your desk.
Observe the penny but don’t touch it. What happens?
Explain why
2. Give the penny a little push. What happened?
Why did the penny move the second time and not the first time?
What was added the second time and not the first time?

3. Chemical Reactions Release and Absorb Energy
Energy is neither created or destroyed, it continues to be transferred.
All Chemical reactions involve a change/transfer in energy.
Potential Energy
Potential to Kinetic Energy
Potential Energy
Potential Energy

4. Observing a Chemical Reaction
Put 50 mL of water into a flask
Add 10 drops of Bromothymol Blue (an acid indicator which will turn the solution yellow if an acid is present)
Get the temperature in `C.
Add one Alka Seltzer tablet (split into two)
Observe reaction and write down observations
Get the temperature after the reaction occurs.
What you observed was:
CO2 + H2O H2CO3 (Carbonic Acid)
Reactants Product

5. Energy is needed to start a Chemical Reaction
Activation Energy is the amount of energy that needs to be absorbed to start a chemical reaction
The push to get the boulder to go down the hill
Activation Energy

6. Do you have this bottle at home?
What is it?
What is it used for?
Can you keep it in your medicine cabinet forever?
Why?
Hydrogen Peroxide
Disinfecting a wound
NO!!
It will naturally break down into Water and Oxygen

7. What happened when the Manganese Dioxide was added to the 3% Hydrogen Peroxide?

8. What happened when the Manganese Dioxide was added to the 30% Hydrogen Peroxide?

9. How can we reduce the amount of activation energy needed to get a reaction started?
2H2O H2O + O2
This reaction will occur on its own but will take a long time and a lot of activation energy
Catalysts reduce the amount of activation energy necessary to get a reaction started
This is a method of cleaning contact lenses using a Manganese dioxide disk which will quickly break hydrogen peroxide into water in oxygen and get your contacts totally disinfected!!
The Manganese dioxide disk can be used over and over again without a loss of functioning.

10. A Chemical Reaction with and without a catalyst
The Catalyst decreased the amount of activation energy needed to get the reaction started

11. Does anyone suffer from eating…?
…Beans, peanuts, broccoli, cauliflower, Brussel sprouts, cabbage, peppers, onions…?
You know what I am talking about!!!
This happens because we can’t digest
alpha-galactose present in these foods
There is something to prevent this!!
Beano contains the Enzyme alpha-galactosidase to allow us to break down alpha-galactose

12. What is the name of the sugar found in milk
What is the name of the sugar found in milk? Maybe you can’t tolerate lactose sugar and are lactose intolerant. What do people do who are lactose intolerant? They take Lactaid pills which contain the enzyme Lactase We will do a lab on this Enzymes are protein catalysts made by living organisms that reduce the amount of activation energy necessary to start and control the rate of a chemical reaction
Lactose

13. Our cells always produce Hydrogen Peroxide
Our cells always produce Hydrogen Peroxide. 2H2O2 2H2O + O2 This is highly toxic to our cells. An enzyme called catalase will allow hydrogen peroxide to quickly break down to water and oxygen. You have seen this with a cut and blood when you put hydrogen peroxide on it. One catalase molecule can convert 40 million of molecules of hydrogen peroxide to water and oxygen each second

14. Characteristics of Enzymes
Made up of Proteins
Are specific to whatever they act upon
Are reusable – don’t get used up in a chemical reaction
Usually have names ending in “ase”
Enter directly into a reaction

15. How Enzymes work
Their shape is specific to what they act upon (the substrate)
They will bind directly to the substrate as an enzyme-substrate complex
The binding site is called the Active Site
A substrate and its enzyme fit together like puzzle pieces – Lock and Key Theory

17. Substrate

18. What can influence an enzymes reactivity?
Temperature
Since enzymes are proteins, their structure can be changed or destroyed by high temperatures.
As temperature increases, the rate of enzyme activity increases to a point then quickly decreases.
Study Island Virtual lab
In us, this temperature is at ~ 40`C

19. pH
Too high or too low pHs will effect the enzyme activity and possibly change its shape.
Lactase activity virtual lab
Different for different organs

20. Concentration of enzymes
As the number of enzymes increases, the rate of reaction increases also to a point where all the enzymes are already bound to an active site of a substrate.
Additional enzymes won’t speed up a reaction at this point.

21. Review
To which biomolecule group do enzymes belong to and usually end in …?
2. What is an enzyme?
What do enzymes do?
4. What part of the enzyme enters into a reaction?
Proteins, -ine
Organic catalyst
Controls the rate of a reaction
Active Site

22. What is the term used for the molecule which is acted on by the enzyme?
When the two are together, what is it now called?
What will extreme pH’s and temperatures do to the active sites of enzymes?
What is the ideal pH and temperature for most reactions in our body?
Substrate
Enzyme-Substrate Complex
Denature the active site – Change the shape
~6.5 – 7.4 & 37`C

23. Label the diagram using the terms, Product, substrate, enzyme, active site and, enzyme-substrate complex.