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Investigating the properties of enzymes.

Extracts from this document...

Introduction

Background Enzymes are proteins. They are biological catalysts that speed up reactions. An example of enzyme action is digestion, where large food molecules are broken down into simple small molecule that can be absorbed across the gut wall into the blood. Enzymes are said to be specific, that is that the enzyme will only work on one food or substrate to produce the products. All living organisms during their metabolism produce Hydrogen Peroxide as a waste substance in many cells. (The enzyme is found in every living cell). This Hydrogen Peroxide is toxic and very dangerous and so must immediately be broken down into harmless products. For this reason every cell has the enzyme catalase which breaks up the Hydrogen Peroxide into water and oxygen. Catalase + H2O2 H20 + 02 The reason why enzymes can only break down one substrate is because of their active sites. Enzymes are 3 -D proteins which have on their surface a code. The substrate has the same code on its surface and the two lock together. The enzyme tweeks the substrate molecule and the two products are separated and released. The enzyme is freed to be used again. Properties of enzymes 1. Enzymes are biological catalysts which speed up reactions 2. They are 3 - D proteins with active site 3. Enzymes are said to be specific - each enzyme only has one substrate which it locks into. ...read more.

Middle

The chip is left to equilibrate for 30 seconds. Then I will start the stopwatch and begin counting the bubbles for 5 minutes which will appear in the test tube filled with water. Once the 5 minutes has ended, I will take the temperature of the solution. The hydrogen peroxide is poured down the sink and the chip is thrown into the bin but the water in the test tube can remain the same Then I will take another chip measuring 5cm. This will be cut into half, placed on a tile and cut with a knife, which will increase the surface area which increases the amount of exposed enzyme but I have to make sure that I cut the chip vertically because if it is not vertical, the surface area would increase. Again I will take 20ml of hydrogen peroxide into a syringe. The chips will be placed in the side arm test tube and I will pour the hydrogen peroxide. Carefully the bung will be placed. It will equilibrate for 30 seconds and then I will start counting for 5 minutes. The chip is then cut into 4 pieces and the same procedure is repeated. Then it will be cut into 8, 16, 32 pieces each time doubling its surface area. The whole experiment is repeated again using another 6 potato chips cut into 2, 4, 8, 16, 32 pieces. ...read more.

Conclusion

I found it difficult drawing my line of best fit because my results were spread out and also the knife I was using to cut my potato chips with was blunt therefore some pieces might have been vertically cut without being realized. This would increase the surface area making it bigger and so it would not be a fair test. During the experiment I experienced a lot of faults and errors. It was difficult to count the number of bubbles and watch the stopwatch as well. Therefore I might have missed a number of bubbles or might have over counted some. When I was doing the experiment it was open day and so I got distracted by parents coming round to see the experiment. I estimated the equilibrate time and so I might have left it for too long or too less. The experiment was unfair because the pressure on the force of the bung was different each time. I might have not tightened it enough and so it would be left loose. The temperature of the solution and room changed, I tried to keep the room temperature constant but it was impossible. The temperature went up by a few degrees which could have increased the enzyme action. Also when I cut the chips in pieces and placed them in the hydrogen peroxide, they would cling with each other and would not separate. This would make the surface area lessen. I realized that fresh chips straight from the water seemed to work better than those that were left damp in wet tissue paper. ...read more.

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