1. Enzymes!
Biology

2. Strategy: If the word is underlined, highlight it in your notes!
Enzymes: Page 42
An enzyme is a protein that functions as a catalyst to speed up a chemical reaction in the body.
Continuously recycled over and over again.
ALL enzymes are proteins.
Biological catalyst: speed up rates of reactions inside the cytoplasm.
They control the rate of metabolic reactions in the body.
They lower activation energy (energy needed to get a reaction started).

3. Page 42 Continues
They weaken chemical bonds so molecules can be made or broken down by the body.
Many enzymes have an “ase” ending.
A few popular ones:
Catalase-> breaks down hydrogen peroxide in eukaryotic cells
Sucrose (table sugar) -> sucrase
Lipids-> lipase
Proteins-> Proteases
Amylase-> human saliva, breaks down starch (amylose)
Lactase-> Lactose (milk sugar)
DNA helicase-> unzips the double stranded molecule for replication
DNA polymerase-> enzymes that create DNA molecules by assembling nucleotides

4. Fun Fact! Catalase breaks down hydrogen peroxide in eukaryotic cells.
It’s estimated that 40 million hydrogen peroxides go into a catalase enzyme every second.
Hydrogen peroxide is toxic to our cells in large quantities

5. Enzyme Substrate Complex- Page 43
Steps:
1. Substrate binds to enzyme at the active site.
2. Substrate is changed by the enzyme and converts the reactants into products.
3. Products are released into the body.
4. Once the products are released, the active site is ready for another molecule (substrate) to bind.
5. The process is ongoing, it never stops.

6. An Enzymes Structure Determines its Function- Page 44
Highly specific: catalyze only one chemical reaction-> specific substrate.
Specific 3-dimensional shape.
Substrate is the reactant in the chemical reaction that is catalyzed by the enzyme, the substance that is changed.
Active Site is the region on the enzyme where the substrate attaches. The shape of the active site changes based on the substrate.
Product is what is created after the chemical reaction has occurred.

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This is often referred to as the “Lock and Key Model”
The shape of the active site (“the lock”) determines which substrate (“the key”) will “fit” into the enzyme.

8. Page 45
Lowers activation energy so that the product can form and the chemicals can spontaneously break apart.
Picture from Biology Holt McDougal text, 2012

9. Factors that Affect Enzymes- page 46
1. Temperature: As temperature increases, kinetic energy increases and molecules move around a lot more. The more they move around, the probability that an enzyme and a substrate will bind together and react increases.
Enzyme reaction increases with an increase in temperature.
Optimal temperature is where the enzyme works best!
98.6 F or 37 C
TOO COLD: Enzymes work slowly or not at all!
TOO HOT: The enzyme denatures / falls apart.

10. Still on page 46 pH: works best at a certain pH.
Sensitive to changes in pH, especially acidity
Too low or too high, the enzyme will DENATURE (fall apart).
EXCEPTIONS:
Digestive enzymes work best at a pH of 3 or 4! Your stomach is very acidic!
OPTIMAL pH is 8

11. https://www. google. com/url

12. #3- Concentration of Enzyme or Substrate: Page 47
If enzyme concentration is low the reaction is slow!
As enzyme concentration increases, the rate of reaction increases.

13. Page 47 continues
As substrate increases, the reaction increases up to a certain point (enzyme is limited).

14. Enzyme Substrate Complex: Graphing and Manipulative Lab- Page 48

15. Videos https://www.youtube.com/watch?v=NdMVRL4oaUo

16. Review Questions: complete on a separate sheet of paper
1. Describe two functions of catalysts in chemical reactions.
2. The substrate is also known as the ___________ in a chemical reaction.
3. Enzymes are made up of _______________
4. List three ways in which enzymes can be altered.
5. Some organisms live in very hot or very acidic environments. Would their enzymes function in a person’s cells? Why or why not?
6. Suppose that the amino acids that make up an enzyme’s active site are changed. How might this change affect the enzyme?