• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6
  7. 7
  8. 8
  9. 9
  10. 10
  11. 11

The Action of Enzymes

Extracts from this document...


The Action of Enzymes PLAN Background information (theory) In our body, large molecules of food that we eat need to be broken down into smaller ones so that they can be absorbed into the bloodstream (otherwise they would be too big to do so). Our bodies alone can do this but it takes such a long time that human life wouldn't exist anymore because we wouldn't get the required nutrients quick enough to survive. Therefore, our bodies use enzymes to speed up these chemical reactions that take place in our bodies. They do this by lowering the activation energy of the reaction so that it can take place at a lower temperature. Enzymes are biological catalysts, which means that they do not get used up during the reaction because they are not chemically changed during a reaction and can be used over an over again by our bodies. This all means that enzymes are needed in only small quantities as they are efficient and work quickly. There are two types of enzymes. Both are made inside cells but one of them leaves the cell and it works outside it. These enzymes are called extracellular enzymes (also called exoenzymes). These enzymes usually break down large food molecules which cannot enter the cell into smaller ones so that they can enter the cell. The other type of enzyme are called intracellular enzymes (also called endoenzymes). These enzymes speed up chemical reactions inside our cells and also control them. During the reaction, the substance in which an enzyme acts on is called the substrate. The new substances made from each reaction are called the products. So when a reaction is happening, the different types of enzymes and substrates are moving about in different directions. So when a substrate molecule bumps into the right enzyme, it fits into a depression in the enzyme. This depression is called the active site. ...read more.


This is what the end point for the reaction will be. Firstly, I will draw a cross on a piece of paper. I will place the beaker with the test-tubes inside it on top of the cross. As the reaction starts to go clear after a while, I will stop the stopwatch when I can see through the reaction and onto the cross. I will do the same for each temperature. Controlled variable - these are the things which I will need to keep the same during the reactions. Therefore, I will use 4g of milk and 0.5g of trypsin in 100cm3 of water for each reaction. This is to keep it a fair test. If I use more trypsin, then there will be more enzymes to break down the milk, so the rate of reaction will be quicker and the solution will turn clear quicker. If I use more milk, it will take the trypsin longer to break down the milk, as there will be more molecules of milk to break down, so the rate of reaction will decrease and the reaction will take longer to turn clear. I will also need to keep the pH of each reaction the same. This is because the pH can affect enzyme activity. If the pH is a lot lower or a lot higher than the optimum temperature for the trypsin, it may denature and the reaction will happen slower and the rate of reaction will decrease. Method 1. I will put 100cm3 of water into a beaker and will make sure that the temperature of the water is at normal room temperature. 2. On a piece of paper, I will draw a cross on it and place the beaker on top of the cross. 3. In a test-tube, I will add 4g of milk. I will then add 0.5g of trypsin and as soon as the trypsin hits the milk, I will start the stopwatch and place the test-tube inside the beaker. ...read more.


However, I thought that the procedure was suitable for the investigation. For example, I was using the right enzyme for the right substrate, i.e. trypsin on casein. I thought that drawing a cross to see when the reaction was over was a good idea because it gave me the chance to record a result without waiting too long for it. However, this could have changed some of the results, because it depended on when I thought the reaction had ended, and not when it had actually ended. However, I only found one anomaly from my results for 25oC, but it did not affect the line of best fit at all. The equipment could have increased or decreased the amount of enzyme and substrate I put in the reaction, but this would have been such a small difference, that I doubt it could have affected the results greatly. For example, if I measured and put in a little bit more of trypsin than was needed, there would have been more enzymes which would have broken down more substrate which could have decreased the reaction time, thus increasing the rate of reaction. Also, I had one anomalous result. I thought that it was anomalous because a long way off the line of best fit. This could have been caused by a human error during the reaction. This may have been because I measured the temperature, and then waited a long time before starting the reaction, so the reaction could have cooled down and the reaction time could have been changed. One way I could have improved the experiment would have been to found a better way of finding when the reaction had ended. The way I did it was to draw a cross under the beaker, and when I could see the cross, measure the time and record it. However, there were problems with this which I have mentioned above. A way I could have improved this method would have been to let the reaction finish completely before recording the result. ?? ?? ?? ?? Biology coursework ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Life Processes & Cells section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Life Processes & Cells essays

  1. Marked by a teacher

    Biology Coursework Enzymes

    4 star(s)

    I think that as the starch concentration is increased the time taken for the amylase to break down the starch will decrease as amylase acts as a catalyst. I predict this because as the concentration of starch is increased there are less water molecules so the chances of reactions are much higher than they would at low starch concentration.

  2. Enzymes experiment. Do enzymes work faster or slower when the temperature is high?

    I will be using one measuring cylinder to measure the amount of protease I need. I used the measuring cylinder because I can measure the amount of protease that I am going to use and that would be 6ml I will wear a pair of Goggles to protect my eyes.

  1. Investigating an enzyme-catalyzed reaction

    didn't go very well because it took me too long to get it all prepared and wasn't very practical. So I decided to use the yeast solution in the end as they were very easy to prepare and were reliable.

  2. Investigation Into Trypsin Activity

    Concentration of Trypsin (%) Volume of Trypsin (cm�) Volume of water (cm�) Time taken to go transparent (s) 1 10 0 85 0.2 2 8 270 Conclusion After completing my preliminaries I found out that the time taken for 1cm� of milk to go transparent was to slow, however 5cm�

  1. Science Enzymes Coursework

    As a rule, enzymes do not attack living cells. As soon as a cell dies, however, enzymes that break down protein rapidly digest it. The resistance of the living cell is due to the enzyme's inability to pass through the membrane of the cell as long as the cell lives.

  2. In my coursework I am investigating the rate of an enzyme action and what ...

    * Measure 1cm� of potato, apple and carrot using a ruler and cut to appropriate level. * Place 1cm� potato into test tube and time for three minutes. * After three minutes, measure the level of froth at the top of the first test tube( using a ruler), and do the same again in another test tube.

  1. Find out how a certain factor that is changed will affect the reaction rate ...

    As the temperature continues to increase the rate of reaction will continue to increase but after a certain temperature the enzyme molecules vibrate so energetically that some of the bonds holding the enzyme molecule in its precise shape begin to break, and the enzyme, especially the active site, loses its shape and so the enzyme can no longer work.

  2. Investigating the effect of temperature on the rate of enzyme action

    They separate off from the complex and the enzyme molecule is left unchanged and ready for the next combination. This happens again and again, speeding up the breakdown of the substrate. The 'Lock and Key Theory' Latest thinking on the lock and key theory has changed our view of how

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work