I am trying to find out what happens if I change the surface area of a potato cylinder and whether or not the amount of oxygen produced by the enzyme catalase changes.

Aim:

Prediction:

I predict that the larger the surface area of the potato cylinder, the more oxygen there is produced.

The scientific evidence that supports my prediction is because there is more surface areas, there are more enzymes so therefore more active sites. The active sites are what produce the oxygen so the more active sites exposed the more oxygen there is produced.

Information about enzymes!

What are enzymes? Enzymes are biological catalysts. They speed up chemical reactions in all living things, and allow them to occur more easily. They occur in plant cells and animal cells. Without them we would not be alive. Enzymes are proteins. They are very important substances because they control the chemical reactions that happen in our bodies. They are known as biological catalysts (substances which speed up reactions but which do not get used up themselves).

There are two main types of enzyme:

Intracellular enzymes that control reactions that occur inside cells.
Extracellular enzymes that control reactions that occur outside cells (for example, digestive enzymes work outside cells in the gut).

Types of enzyme

Enzyme names usually end in the letters 'ase'.

Carbohydrases turn carbohydrates into simple sugars. For example, amylase turns starch into maltose.
Lipases, such as lipase, turn fats into fatty acids and glycerol.
Proteases, such as pepsin, turn proteins into amino acids.

The enzyme has an active site that ...

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There are two main types of enzyme:

Intracellular enzymes that control reactions that occur inside cells.
Extracellular enzymes that control reactions that occur outside cells (for example, digestive enzymes work outside cells in the gut).

Types of enzyme

Enzyme names usually end in the letters 'ase'.

Carbohydrases turn carbohydrates into simple sugars. For example, amylase turns starch into maltose.
Lipases, such as lipase, turn fats into fatty acids and glycerol.
Proteases, such as pepsin, turn proteins into amino acids.

The enzyme has an active site that helps it to recognise its substrate in a very specific way. Just like a key only fits into a specific lock, each enzyme has its own specific substrate. This is called the lock and key theory.

Although they work powerfully, enzymes are just chemical molecules, made up of proteins. They are too small to be seen either when they are inside cells or after they have been released from them, for example in the digestive system. Each particular enzyme has a unique, 3-dimensional shape shared by all its molecules. Within this shape there is an area called the active site where the chemical reactions occur.

The effect of temperature on enzyme action

Temperature is important in all reactions. As the temperature increases, so does the rate of reaction. This is because heat energy causes more collisions between the particles in the enzyme and particles in the substrate. However, very high temperatures damage enzymes by denaturing them.

The effect of pH on enzyme action

Different enzymes work best at different pH values.

The optimal (best) pH for an enzyme depends on its site of action. For example, enzymes in the stomach have an optimum pH of about 2 because the stomach is acid, but intestinal enzymes have an optimum pH of about 7.5.

The uses of enzymes

The specificity of enzymes and the fact that they speed up reactions makes them very useful to humans in commerce and medicine.

Sources:

http://www.s-cool.co.uk

Planning my experiment!

To test my prediction I have planned out an experiment using the following apparatus:

Two clamp stands
Two clamps
Boiling tube
Water-filled beaker
Delivery tube
Potato cylinders
Hydrogen peroxide
Cork bung
Tap burette

Here is my method:

The potato will be placed inside the boiling tube with some hydrogen peroxide. As the potato reacts with the hydrogen peroxide, oxygen is given off and collects in the tap burette. The tap burette is filled with water so that I can tell how much oxygen the potato and hydrogen peroxide is giving off. I will then relate it to the measurement of the potato cylinders and their surface areas. In theory, the larger the surface area of the potato, the more enzymes there are to produce the oxygen.

The results will be put into a table similar to this one:

To make my results reliable and a fair test I will keep the volume of the potato the same, the temperature the same and the volume of the hydrogen peroxide the same.