How does the concentration of hydrogen peroxide (substrate) affect the enzymatic activity of catalase by measuring the volume of oxygen produced?

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Claudia Cheng

IA 6: Unit 3- Enzyme Investigation

Design

Introduction

An enzyme is a biological catalyst that alters the rate of a reaction (and lowers the activation energy) without being changed itself. Enzymes are three dimensional shape proteins that have a very specific active site. “In enzymatic reactions, substrates are converted into different molecules also known as products. Since enzymes are very selective for their substrates, each enzyme can only convert one kind of substrate into one kind of product molecule. 

Catalase is an enzyme found in most living organisms and is one of the fastest reacting catalysts known. Catalase breaks down hydrogen peroxide into water and oxygen. An equation for this reaction is shown below. An example of a catalase enzyme is carrots, which is going to be used in this investigation.

 Formula for catalase reaction:

Hydrogen peroxide  Water + Oxygen

H2O2   H2O + O2 

Research Question

How does the concentration of hydrogen peroxide (substrate) affect the enzymatic activity of catalase by measuring the volume of oxygen produced?

Hypothesis

If catalase is added to the varying levels of dilution of hydrogen peroxide samples, the solution with the highest substrate concentration will yield the most activity, thus producing more oxygen gas. This assumption is based on scientific theory, which states that higher substrate concentrations increase the ability of enzymes to catalyze reactions.  As substrate concentration increases, the amount of substrate per unit volume increases. So it is more likely for the substrate to bind to the active site of the enzyme with the correct orientation forming the enzyme substrate complex, leading to the formation of the products. This means enzyme activity increases and the rate of reaction also increases. However, enzyme saturations limits the reaction rate. At which, the reaction will not speed up however concentrated the substrate is due to the active sites of that enzyme being fully occupied already.  

Independent and dependent variables

Controlled variables

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Equipment

  • Delivery tube
  • Gas syringe
  • Stopwatch
  • 5 Conical flasks
  • Clamp stand
  • Blender
  • Knife
  • Tile
  • 2 Measuring cylinder
  • Funnel
  • Filter paper
  • 500ml beaker
  • 2 carrots
  • Hydrogen peroxide
  • Distilled water
  • Bung


Risk Assessment

  • Take caution as harmful chemicals will be used (hydrogen peroxide)
  • Safety clothing (goggles, lab coat, sensible shoes) should be worn to ensure the protection of skin
  • Glass equipment to be handled with care to avoid glass breakage
  • Long hair should be tied back

Diagram

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