Biology Investigation: Investigating the Effect of Catalase Concentration on the Speed of Reaction with Hydrogen Peroxide

Biology investigation: Investigating the effect of Catalase concentration on the speed of reaction with Hydrogen Peroxide

Planning 2

Aim: 2

Prediction 2

Research 2

What is Catalase? What does it do? 2

How could I measure the rate of reaction? 3

Is this method viable? 3

How can I make sure that my results are fair? 4

How will I control my variables? 6

What are the risks? 7

Method 7

Equipment 7

What will gain/lose oxygen in my experiment? 9

Final Method 10

Implementation 10

Table of results 10

Graphs 11

A graph to show cumulative oxygen produced in cm cubed when reacting 1 to 5 percent yeast concentration with 2 ml hydrogen peroxide 11

A graph to show the gradients of each yeast concentration 11

Analysis 12

Graph analysis 12

Cumulative oxygen graph analysis 12

Calculating my gradients 12

Gradient graph conclusion 13

Evaluation 15

Anomalous results 15

Error 15

Percentage error of equipment 15

Main sources of error 16

My new method 16

Equipment: 16

Final Method 18

Changes 18

Is my conclusion valid? 19

Planning

Aim:

Investigating the effect of Catalase concentration on the speed of reaction with Hydrogen Peroxide

Prediction

Based on my research I predict that the greater the concentration of enzyme, the faster the rate of reaction.

The more enzyme present, the more chance there is of a successful collision occurring between the substrate and the enzyme, in order to form an enzyme-substrate complex. [Kinetic theory]. The hydrogen peroxide will react with the prosthetic iron group in the Catalase [specifically amino acids His 74 and Asn 174]. This breaks the double bond between the hydrogen heterolytically. The oxygen formed will react with the enzyme active site and displace the water that has formed there from the above reaction. This cycle will continue until there is no Hydrogen Peroxide left.

Source- www.wikipedia.org/catalase

To do this, the enzyme 'changes its form slightly' [Essential OCR Biology - Glen & Susan Toole] in order to react with the substrate. By altering its shape, the enzyme induces pressure onto the substrate, therefore lowering its activation energy. The lock and key theory however is based on the principle of the enzymes specific nature. According to this theory, the substrate fits perfectly into the enzyme active site. Source: Essential OCR Biology - Glen & Susan Toole

The enzyme is specific due to its structure. The Primary structure of Catalase is the sequence of amino acids that make up the protein [Catalase has 506 amino acids, as well as one haem group]. The Secondary structure is the manipulation of these sequences with hydrogen bonds. The amino acids are manipulated into Alpha helixes [26% of Catalase's structure]; Beta pleated sheets [12%] and other irregular arrangements. The Tertiary structure consists of other bonding types- ionic, hydrophobic, disulphide and further hydrogen bonds. The quaternary structure of Catalase includes the prosthetic haem group. If any of these structures are altered, the protein cannot act as a site of reaction.

Source-http: //www.clunet.edu/BioDev/omm/catalase/frames/cattx.htm

Research

What is Catalase? What does it do?

Catalase is an enzyme. It is a naturally occurring globular protein found residing in cell 'sacs' called Perisomes. Catalase is vital because it catalyses the breakdown of harmful Hydrogen Peroxide into water and oxygen. Without Catalase, Hydrogen Peroxide accumulates in the liver and effectively dissolves the organ. This is potentially fatal. Catalase is specific to Hydrogen Peroxide- it will not Catalase any other reaction. This is because of its specific shape.

2H2O2 --> 2H2O + O2

The hydrogen peroxide reacts with the prosthetic iron group in the Catalase [specifically amino acids His 74 and Asn 174]. This breaks the double bond between the hydrogen heterolytically. The oxygen formed reacts with the enzymes active site and displaces the water that has formed there from the above reaction. This cycle continues until there is no Hydrogen Peroxide left. Source-www.wikipedia.org/catalase

Catalase is able to form the enzyme-substrate complex in order to break down Hydrogen Peroxide. The method is called the induced fit theory. This states that the enzyme 'changes its form slightly' [Essential OCR Biology - Glen & Susan Toole] in order to react with the substrate. By altering its shape, the enzyme induces pressure onto the substrate, therefore lowering its activation energy. The lock and key theory however is based on the principle of the enzymes specific nature. According to this theory, the substrate fits perfectly into the enzyme active site:

How could I measure the rate of reaction?

Catalase produces oxygen as it breaks down Hydrogen Peroxide. This could easily be measured in a quantitative way, as it should vary according to the enzyme effectiveness would put these results into a table, and create a graph. I could use the graph to calculate the gradient,