Bio Lab Report Enzyme Activity

Name: Natasha Chan Li Chyi

Student ID: 1701G104053

Topic: Biology Report

Introduction:

Enzymes are biological catalysts that speed up reactions that occur inside living organisms. In an enzyme-catalysed reaction, the substrate binds to the active site and forms enzyme-substrate complex with the enzyme. The enzyme then breaks the bonds in the substrate. The product of the reaction then leaves the enzyme, which remains unchanged after the reaction.

Catalase is an enzyme produced by the liver to to break down hydrogen peroxide (a common end product of metabolism, but highly toxic if accumulated in the body) into water and oxygen according to the following reaction:

Catalase

Hydrogen peroxide                             Water + Oxygen[pic 1]

2H2O2                                        2H2O + O2[pic 2]

In this experiment, the volume of foam produced in the measuring cylinder will be measured after 2 minutes of reaction to measure the rate of enzyme-catalysed reaction.

Aim:

To investigate how the pH of a substrate may influence the rate of enzyme-catalysed reaction

Hypothesis:

The rate of reaction will increase with the increase of pH of the hydrogen peroxide, if the other factors of enzyme activity are kept constant. However, the rate of reaction will decrease with the continuously increasing of pH of the hydrogen peroxide at a point pass the optimum pH for the enzyme to work best in.

Variables:

Independent variable: The pH of the hydrogen peroxide (pH)

Dependent variable: The rate of enzyme-catalysed reaction (mL/min)

Constant variables: 1.00% concentration of the hydrogen peroxide, 1cm3 of the liver, 30˚c as the surrounding temperature, 9cm3 of the hydrogen peroxide solution, time given for reaction

Apparatus and Materials:

• Hydrogen peroxide solution of different pH levels (pH 5, pH7, pH9, and pH12)
• Detergent
• Fresh chicken liver
• Stopwatch x4
• 10 mL measuring cylinder x4
• Forceps x4
• Ruler x4
• 100mL measuring cylinderx4
• Distilled water
• White tile x4
• Teat pipette x4
• Pipette dropper
• Scalpel x4

Method:

1. 4 cubes of liver were cut with a ruler and a scalpel with each approximately 1cmx1cmx1cm.
2. 9mL of hydrogen peroxide with a pH of 5 was measured with a teat pipette into a 10mL measuring cylinder. The 9mL of hydrogen peroxide was then transferred into the 100mL measuring cylinder. A drop of detergent was then added and the measuring cylinder was swirled to mix the solution.
3. One cube of liver was taken with a forceps and it was placed in the measuring cylinder. The stopwatch was started immediately. After two minutes, the total volume of foam in the cylinder was recorded into a table.
4. Steps 2-3 were repeated with the other 3 different solutions of hydrogen peroxide.
5. The average of the volumes for each pH of hydrogen peroxide were calculated and recorded. The rate of reactions were calculated by the following formula:

Rate of reaction (mL/min)= Average total volume- 10

                                                                                     2 mins

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