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Enzyme Action: Exploring Catalase Activity and Environmental Factors, Lab Reports of Biology

Pre lab questions with procedure and conclusions of catalase enzyme lab

Typology: Lab Reports

2020/2021

Uploaded on 05/11/2021

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ENZYME ACTION
Introduction: Catalysts are substances that speed up chemical reactions. Organic catalysts are called
enzymes. Catalase is an enzyme normally found in many plant and animal tissues. The biological
purpose of catalase is to destroy toxic substances that may be introduced into cells. Also, some cells use
catalase to destroy cellular debris or worn out organelles. In this lab, we will use a catalase solution
from potatoes and determine the effect of temperature and pH on the action of this enzyme. The substrate
of the enzyme will be 3% hydrogen peroxide (H2O2). Catalase works by the following mechanism:
2 H2O2 --------->2 H2O + O2
The development of oxygen gas can be observed by the foam produced in a test tube.
Materials:
Eye protection Metric ruler
Red-skinned potatoes Test tube rack
Scalpel or knife (for cutting and mashing the potato) Marker pen or pencil
H2O2 Test tube clamps
Test tubes acid (HCl)
Hot water bath base (NaOH)
Ice bath Rocks or pebbles
pH paper
CAUTION! HCl and NaOH are strong acids and bases. If you spill these chemicals on your skin,
immediately wash in running water. Wear eye protection at all times. Be careful of hot water and
hot plates.
Pre Lab Questions (Need help? Use pg. 57 in the Modern Biology text)
1. What type of biological molecules are enzymes? (circle one)
a. proteins b. carbohydrates c. lipids d. nucleic acids
2. Describe how an enzyme works and its importance to all living organisms.
3. TRACE the diagram of enzyme action on page 57 of your textbook, below. Label the appropriate
parts of the picture: catalase, H2O2, H2O, and O2
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ENZYME ACTION

Introduction: Catalysts are substances that speed up chemical reactions. Organic catalysts are called enzymes. Catalase is an enzyme normally found in many plant and animal tissues. The biological purpose of catalase is to destroy toxic substances that may be introduced into cells. Also, some cells use catalase to destroy cellular debris or worn out organelles. In this lab, we will use a catalase solution from potatoes and determine the effect of temperature and pH on the action of this enzyme. The substrate of the enzyme will be 3% hydrogen peroxide (H 2 O 2 ). Catalase works by the following mechanism:

2 H 2 O 2 --------->2 H 2 O + O 2

The development of oxygen gas can be observed by the foam produced in a test tube.

Materials:

Eye protection Metric ruler Red-skinned potatoes Test tube rack Scalpel or knife (for cutting and mashing the potato) Marker pen or pencil H 2 O 2 Test tube clamps Test tubes acid (HCl) Hot water bath base (NaOH) Ice bath Rocks or pebbles pH paper

CAUTION! HCl and NaOH are strong acids and bases. If you spill these chemicals on your skin, immediately wash in running water. Wear eye protection at all times. Be careful of hot water and hot plates.

Pre Lab Questions (Need help? Use pg. 57 in the Modern Biology text)

  1. What type of biological molecules are enzymes? (circle one) a. proteins b. carbohydrates c. lipids d. nucleic acids
  2. Describe how an enzyme works and its importance to all living organisms.
  3. TRACE the diagram of enzyme action on page 57 of your textbook, below. Labe l the appropriate parts of the picture: catalase, H 2 O 2 , H 2 O, and O 2
  1. Define the following terms as they apply to enzymes:

a) Active site:

b) Substrate:

c) Denature:

Part A: Exploring Catalase Activity

Procedure :

  1. Label 4 test tubes 1, 2, 3, 4 and mark each at the 3cm mark with a marker pen or pencil.
  2. Fill tube 1 to the 3cm mark with hydrogen peroxide, and then drop a small rock or pebble in.
  3. Cut three 1cm^3 cubes of potato, minus the skin.
  4. Fill tube 2 to the 3cm mark with hydrogen peroxide, then drop in one potato cube.
  5. Fill tube 3 to the 3cm mark with hydrogen peroxide, then mash or chop up a potato cube and add it to the tube.
  6. Fill tube 4 to the 3cm mark with water, then mash or chop up a potato cube and add it to the tube.

Observe the reactions in the 4 tubes for 5 minutes. Note how vigorously each reaction โ€œbubblesโ€ (emits oxygen gas) in Table 1. Using a metric ruler, measure the height of the bubbles produced after 5 minutes.

Part A: Results and Observations: After adding the H 2 O 2 , watch the clock and record activity based on oxygen bubbles (product) given off. Rate the activity for each test tube using the following rating scale and complete Table 1 with these symbols:

      • extremely active bubbling; foamy
    • good bubbling
  • moderate bubbling 0 nonreactive; no bubbling

Table 1: Activity of Enzyme on Hydrogen Substrate Decomposition tube Test tube First minute activity rating

5 minute activity rating

Height of bubbles (cm)

Scientific explanation

1 Pebble in H 2 O 2

2 Potato cube and H 2 O 2 3 Chopped potato and H 2 O 2 4 Chopped potato and water

Part B

Data:

Table 2: Effect of Temperature on Catalase Reactions Test tube Temperature (oC) Height of Bubbles (cm)

Hot

Room Temp

Cold

  1. What effect did (a) heat have on the activity of the enzyme? (b) What effect did cold have? (c) Room Temperature?
  2. What were the controls in this experiment?
  3. Which test tube reacted the least? What scientific reasons can you give for this?
  4. In a few sentences, summarize your findings from Table 2 , here:

Part C: The Effect of pH on Enzyme Activity:

  1. Label 3 test tubes โ€œ 1 โ€, โ€œ 2 โ€ and โ€œ 3 โ€. Mark each to the 3 cm mark with a marker pen or pencil.
  2. Place a 1cm^3 of potato into each test tube.
  3. Add 10 drops of HCl to the tube labeled โ€œ 1 โ€, 10 drops of NaOH to the tube labeled โ€œ 2 โ€ and 10 drops of distilled water to the tube labeled โ€œ 3 โ€. Mix contents by gently swirling. Test the pH of each using a pH stick.
  4. Wait 2 minutes, then add H 2 O 2 to the 3cm mark in each tube.
  5. Wait 5 minutes for reaction to occur, then measure the height of the bubbles in cm. Record in Table 3.

Table 3: Effect of pH on Catalase Reactions

pH

Height of Bubbles (cm)

Comments:

Acid

Neutral

Base

Analysis and Conclusions:

  1. What effect did (a) lowering the pH have on the activity of the enzyme? (b) Raising the pH?
  2. What were the controls in this experiment?
  3. Which test tube reacted the least? What scientific reasons can you give for this?
  4. In a few sentences, summarize your findings from Table 3 , here: