Enzymes Lab Report

BioLab3

Enzymes Lab Report

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The lab report is unique each semester and checks have been put into place to ensure students are doing their own work. Copying from other students or from outside sources will result in a zero on the accompanying lab quiz.

I. Enzyme Structure and Function

1. In Ex 1 observe the diagram of the enzyme reaction.
The enzyme is: An enzyme is a biocatalyst which increase the rate of a chemical reaction without changing itself in the whole process. In an organism most of the cellular processes are mediated by enzymes.
The substrate is: It is an molecule upon which an enzyme acts and give rise to product. Enzymes are highly specific for substrates. when an enzyme binds to a specific substrate then it forms enzyme-substrate complex.
The gas needed for this reaction:
The product is:

2. Explain why fruit turns brown upon exposure to air.

3. Explain how enzymes function in the enzyme-substrate complex.

4. In Ex 1 a color intensity scale is created for enzyme activity. Using the numbers on the color intensity scale record the data of the solution in each test tube at five and ten minutes.

Time
(min) Tube S1
Potato Extract + Catechol Tube S2
Potato Extract + Water Tube S3
Catechol + Water
0 YELLOW MILKY CLEAR TO MILKY
5 YELLOW LIGHT PINK CLEAR TO MILKY
10 ORANGE PINK CLEAR

5. A brownish-amber color indicates the presence of:

6. Which two solutions need to be present to detect benzoquinone?
a.
b.

II. Enzyme Specificity

1. In Ex 2 observe the structural formula of catechol and hydroquinone. How do they differ?

2. Compare the two test tubes one with catechol and one with hydroquinone. After 10 minutes the color intensity of catechol was ______ and hydroquinone was ______.

3. This result showed that the enzyme catechol oxidase reacted best with the substrate

4. What is the role of hydroquinone in this experiment? It plays the role of inhibitor as it inhibited the preocess of autopolymerization which is might not be necessary

III. Temperature and Enzyme Activity

1. Using Ex 3, record the relative color intensity at five-minute intervals to determine the temperature range for catechol oxidase. Record Step 6 data in row 1, Step 7a data in row 2, Step 7b data in row 3
Time
(min) Tube 1
4oC Tube 2
23oC Tube 3
40oC Tube 4
60oC Tube 5
80oC Tube 6
100oC
1 0 Yellow YELLOW YELLOW YELLOW CLEAR TO MILKY CLEAR TO MILKY
2 5 YELLOWISH ORANGE YELLOWISH ORANGE YELLOWISH ORANGE ORANGE CLEAR TO MILKY CLEAR TO MILKY
3 10 YELLOWISH ORANGE (2) BROWNISH RED ORANGE (5) BROWNISH RED (4) ORANGE (3 ) CLEAR TO MILKY ( 0 ) CLEAR TO MILKY (0 )

2. Construct a bar graph of the data for just the ten-minute readings. Label the axes, Y axis is the 1-5 intensity scale and X axis is temperature. Give the graph a title and provide units. Sign, date and prepare an image of your graph and include it with this lab report.

3. What is the optimal temperature for catechol oxidase activity? 37 degrees celsius

4. The enzyme is denatured at which temperatures? Because enzymes are proteins, they are denatured by heat. Therefore, at higher temperatures (over about 55°C

IV. pH and Enzyme Activity

1. Describe the pH scale. You can do this with a drawing of the pH scale as an option.

2. In Ex 4, fill in the data chart with the numbers of the intensity scale at 10 minutes. Note that pH 10 and pH 12 are gray, but clear.

Time (min) pH2 pH4 pH6 pH7 pH8 pH10 pH12
10

3. Within what pH range will catechol oxidase catalyze catechol and oxygen to form benzoquinone? At pH 7

4. What is the optimum pH for catechol oxidase? Catechol oxidase enzyme has an optimum pH of about 7.

5. Which pH values denature the enzyme? Most other enzymes function within a working pH range of about pH 5-9 with neutral pH 7 being the optimum.

V. Cofactors and Enzyme Activity

1. What is the role of a cofactor for enzymes? A cofactor is a non-protein chemical compound or metallic ion that is required for an enzyme’s role as a catalyst

2. In this experiment copper was the _____________ for catechol oxidase which allowed the enzyme to function effectively.

3. Copper was prevented from helping the enzyme because it bonded to the chemical called _________ when that chemical was added to test tube 1.

Summary Questions

1. Underline or highlight which characteristic is incorrect about enzymes.
a. Enzymes are proteins made in the cells of living organisms
b. Enzymes are used up in their reactions
c. Enzymes act as catalyst to lower the activation energy for reactions to occur
d. enzymes react with a specific substrate that fits into its active site

2. Underline or highlight which characteristic is correct about enzymes.
a. Enzymes can react with many substrates
b. Enzymes can be denatured by extreme temperature or pH
c. Most enzymes names end in the suffix ase
The substrate is destroyed by the enzyme and the leftover atoms combine to form the product

3. Define denatured. to deprive of natural qualities

4. What 3 activities of this lab showed denaturing of the enzyme, catechol oxidase?

5. What is the optimum range of pH and temperature that our bodies provide for the efficient functioning of our enzymes?