Enzyme Activity: Temperature

NAME: Esther Ugraj                                                             BIOLOGY UNIT ONE

LAB No.7                                                                 Skill:

DATE:

TITLE: ENZYME ACTIVITY

AIM:        1. To determine the distribution of catalase in peas.

2. To determine the effect of temperature on its activity.

INTRODUCTION:

Enzymes are biological catalysts. They speed up metabolic reactions in the body but remain chemically unchanged themselves. Enzymes contain an active site. This is a region, normally a depression or cleft, to which another molecule may bind. This molecule is known as the substrate, and is usually specific to the active site of the particular enzyme, which breaks it down. Substrates will not usually fit into any other active sites other than that of the enzyme it is specified to. This can be explained as a lock and key
model, where the lock and key are specific to each other, only, that there are many of the same kinds of lock and key when it come to the enzymes. Just as lock and keys have three-dimensional shapes, proteins are also three-dimensional. Usually, there is only one active site on an enzyme; however there can be more. Some energy releasing reactions in cells produce hydrogen peroxide.

Hydrogen peroxide is released due to many metabolic reactions in the body, which gives toxicity to the living cells. Hence, there is a chemical need to remove hydrogen peroxide in a very rapid rate. In order to avoid this toxicity, the enzyme Catalase is present in sufficient quantities in the cells. Catalase binds with the substrate molecules though their active sites and catalyses’ by processing them to form the ultimate by-products of water and oxygen, at a rapid rate. Every 2 molecules of hydrogen peroxide is broken down into 2 molecules of water and one molecule of oxygen, which are released as the by-products. (2 H2O2   >> 2 H2O + O2  (gas)) This type of

An intensive metabolic activity can be found in soaked pea seeds as they begin to germinate. Hence, their catalytic activity is at higher levels. In order to investigate the effect of temperature on the activity of catalase, the amount of oxygen released when hydrogen
peroxide is broken down is recorded.

APPARATUS/ MATERIALS:

1. 1 pint soaked peas                       7.  Test Tube holder
2. Hydrogen Peroxide                     8.  Glass Rod
3. Test Tube                                    9.  Water Bath
4. Test Tube Rack                          10. White tile
5. Thermometer                             11.  Scissors
6. Forceps

METHOD:

1. The peas were soaked for 24hrs.
2. Three seeds were crushed and placed into a test tube.
3. A few drops of hydrogen peroxide was added to the test tube and observations were recorded.
4. The seed coat was removed from 3 selected soaked peas.
5. The seed coats were placed into a test tube with hydrogen peroxide to the bare cotyledon and observations were made and recorded
6. Three whole peas was boiled
7. Two test tubes of distilled water was placed in a water bath, one containing three boiled peas and the other three unboiled peas for about 10 minutes.
8. Each pea was then tested for catalase activity.
9. Steps 7-8 were repeated using water baths with temperatures of 500C, 600C, 700C, 800C and 1000C respectively.
10. All observations were recorded.

RESULTS:

Table showing the results obtained after peas were tested for the distribution of catalase