1. Aim 7E: How do enzymes control chemical reactions?

2. 1) What are enzymes made up of?
Enzymes are made up of proteins
AKA: Organic Catalysts
Organic- contains carbon and hydrogen
Catalysts- affect the rate of chemical reactions
**enzymes are never used up or changed so they can be reused**

3. 2) How do enzymes function?
Substrate- molecule(s) that an enzyme works on
Active Site- pocket or groove where the chemical reaction takes place (where substrate meets enzyme)
Enzyme-Substrate Complex: substrate temporarily binds to active site (held in by hydrogen or ionic bonds)

4. Short Video: How Enzymes Work McGraw-Hill
hill.com/sites/ /student_view0/chapter2/a nimation__how_enzymes_work.html

5. 3) What are cofactors?
Small molecules that bind with enzymes and are necessary for enzyme function
Inorganic- metal atoms
Organic- coenzymes (most vitamins)

6. 4) What is the Lock and Key Hypothesis?
Enzymes are specific and will only work on one type of substrate

7. 5) What is the Induced Fit Hypothesis?
The enzyme changes shape to enhance the ability of the enzyme to catalyze the chemical reaction
The enzyme returns back to its original shape after the reaction occurs

8. 6) How are enzymes named? Enzymes often end in “-ase”
Lipase- works on lipids
Protease- works on proteins
Maltase- works on maltose

9. 7) What is activation energy (Ea)?
The amount of energy need to START a chemical reaction
How do enzymes affect the activation energy of a chemical reaction?
Enzymes lower the activation energy needed for a reaction to take place

10. 8) What factors affect enzyme reactions?
Temperature- As the temperature increases, the rate of reactions increases then decreases.
Optimum Temperature- the temperature at which the enzyme works best
98. 6 degrees Fahrenheit or 37 degrees Celsius
Denature- high temperature will change the shape of the enzyme so it does not fit anymore

11. 8) What factors affect enzyme reactions?
pH- depends on where enzyme is working in the body
Amylase- breaks down starch in the mouth (pH= 6.2 to 7)
Pepsin- breaks down protein in the stomach (pH= )
Trypsin- breaks down protein in the small intestines (pH= 8)

12. 8) What factors affect enzyme reactions?
c) Enzyme concentration- as more enzymes are added, enzyme action increases and then eventually levels off

13. 8) What factors affect enzyme reactions?
d) Substrate concentration- as more substrate is added, enzyme action increases and eventually levels off

14. Let’s Review! What is an enzyme? What are enzymes made of?
What is a substrate?
Can an enzyme work on any substance?
What letters do enzymes often end in?
What factors affect the rate of enzyme action?

15. Which chemical is classified as an enzyme?
galactose
lipid
protease
manganese dioxide

16. In enzyme controlled reactions, the role of certain vitamins such as niacin is to act as
an enzyme
a substrate
a coenzyme
a polypeptide

17. Salivary amylase is an enzyme in humans that breaks down starch
Salivary amylase is an enzyme in humans that breaks down starch. The optimum pH for this reaction is 6.7. The rate of this reaction would not be affected by 
maintaining the pH of the reaction at 6.7 
substrate concentration 
enzyme concentration 
decreasing the temperature of the reaction by 5 degrees C

18. Which statement best expresses the information represented in the graph shown?
The action of enzymes varies with pH. 
A pH of 7 provides the optimum environment for digestive enzymes 
Gastric juice is active at a pH extending from 0 to 12. 
Acids have a pH greater than 7.

19. Lipase, maltase, and protease are members of a group of catalysts known as 
hormones 
carbohydrates 
lipids 
enzymes

20. The effect of temperature on the relative rate of action of an enzyme is represented in the graph. The optimum temperature for the action of this enzyme is approximately 
15 C 
22 C 
37 C 
50 C

21. Here are of some stages of an enzyme-controlled reaction
Here are of some stages of an enzyme-controlled reaction .  An enzyme-substrate complex is represented by diagram  A  B  C  D

22. The diagram below represents three steps in the hydrolysis of a molecule of sucrose.  In this diagram, structure X is most likely 
a molecule of oxygen 
the end product 
an organic catalyst 
the substrate

23. The fact that amylase in the human small intestine works best at normal body temperature suggests that 
amylase is denatured at temperatures below 37 degrees C 
amylase can function only in the small intestine 
the lock-and-key model of enzyme action does not apply to amylase 
the optimum temperature for amylase is 37 degrees C

24. Which statement best describes the enzyme represented in the graphs?
This enzyme works best at a temperature of 35 C and a pH of 8. 
This enzyme works best at a temperature of 50 C and a pH of 12. 
Temperature and pH have no influence on the activity of this enzyme.  
This enzyme works best at a temperature above 50 C and a pH above 12

25. Use the chart below and your knowledge of the living environment .
If enzyme C is functioning at 25°C and a pH of 7, under which conditions would the rate of enzyme action probably increase? 
The temperature is decreased to 22 C and the pH is kept the same. 
The temperature is kept the same and the pH is decreased to 6. 
The temperature is increased to 44 C and the pH is kept the same. 
The temperature is increased to 30 C and the pH is increased to 8.
At what temperature would enzyme D most likely be denatured? 
15 C 
20 C 
25 C 
39 C

26. Letter A in chemical reaction one most likely represents
a substrate 
a neurotransmitter 
an organic catalyst 
a hormone
Which substance most likely represents letter C in reaction two? 
amylase 
protease 
sucrase 
lipase  
A student placed groups of 50 seeds in a variety of temperatures ranging from 0 to 50 C. A difference in the rate of germination observed in the groups at different temperatures was most likely due to the effect of temperature on 
ammonia 
acids 
enzymes 
cellulose

27. Using your knowledge of enzyme structure and function, explain why a prolonged period of high fever is dangerous to humans.