• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Sam and Sarah planned and carried out an experiment to see the effect of pH on the activity of the enzyme amylase which breaks down starch into sugar.

Extracts from this document...


Carly Mckenzie 17/10/01 Investigation on Enzymes Introduction Sam and Sarah planned and carried out an experiment to see the effect of pH on the activity of the enzyme amylase which breaks down starch into sugar. They decided to investigate 5 different pH's 2,4,6,8 and 10. 1. The used a measuring cylinder to measure out 5cm3 of starch and placed it in a test tube. They then added acid or alkali until they got to pH2. They checked this using indicator paper 2. They placed the test tube in a rack on the bench and added 5cm3 of amylase which they had also measured using a measuring cylinder. 3. Immediately, they took out a drop of the mixture and placed it on a spotting tile which had 2 drops of Iodine in it. They repeated this every 30 seconds until they knew all of the starch had been broken down, so they stopped. 4. They then repeated the experiment at the different pHs'. 5. ...read more.


Starch (the substrate) fits perfectly into the amylases active site and from here can be broken down into sugar (There is a more detailed explanation in the diagram below). When the enzyme is placed in too acidic/alkaline conditions the active site denatures and the substrate no longer fits. My prediction was supported by my graph (on the opposite page) the lowest point on the graph shows the optimum pH which in this case was 8. Therefore my prediction was correct. Evaluation This experiment was reliable in the view that there only appeared to be 1 anomalous result which was 7.6 (min) at a pH 6 when it should've been 6.1 (min) this is shown on the line graph. This result may have been wrong because the experiment didn't utilize tools which were accurate enough such as: - * The universal indicator is not very accurate * It may not have been timed exactly every 30 seconds * Not all of the drops of Iodine ...read more.


This may have affected the accuracy of the end results i.e. the graph. The fact that the gap between the two numbers was so large (2 minutes) also shows how unreliable the experiment is. Sam and Sarah could extend this experiment by using all of the pHs' in the experiment not just the even numbers such as pH 1, 3, 5, 7, 9 etc. They could also extend the experiment further and investigate all pHs' from 7.0 to 9.0 e.g. 7.1, 7.7, 8.3 and 8.9 (obviously with the other pHs' in between) This will show whether the optimum pH is really 8.0 (it could be 7.9 or 8.1). I don't think that the evidence from this experiment is accurate enough to support a conclusion for the previously mentioned reasons. I think that is extremely likely to make mistakes, like I said beforehand the average wasn't 15.7 for that particular pH, this may have made major differences to a conclusion. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Molecules & 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 AS and A Level Molecules & Cells essays

  1. Marked by a teacher

    How does the pH affect the activity of amylase

    3 star(s)

    results, with a huge difference from pH6, with pH8 having an average time of 17.2 minutes. Compared to pH 6 at 6 minutes we can see that there is a big difference of 11 minutes with pH8. Also at a lower; pH4 for example there was a time difference of 7 minutes which was another big difference.

  2. Experiment to Investigate the Effect of Copper Ions on a Solution of Amylase and ...

    Starch concentration- 0.1M of starch must be used throughout the whole of the experiment. As the substrate concentration increases, there are a greater number of substrate molecules which can collide with the amylase molecules. This results in more successful collisions per second thus the rate of reaction increases.

  1. The Effect of Starch Solution on the Activity of Amylase

    The dependent variable: I will be measuring the time it takes for the mixture to reach its achromatic point. Controlled Variable: I will measure the temperature of the solutions when making sure that the mixture in the test tubes reaches the same temperature as the water bath.

  2. Investigating the effect of pH on the activity of an enzyme.

    These values are appropriate to use as they cover a range of pH values of 1-14 as 1 is the lowest pH value and 14 is the highest pH value. ==> Protease solution: This is the enzyme which will be needed to react with the substrate.

  1. Investigating the Effect of pH on Enzymes

    starch solutions containing buffer were placed into the test tubes, each test tube with a different pH solution. Both were done using two separate 5cm� graduated pipettes, so as to give the greatest degree of accuracy and also prevent cross contamination.

  2. An Investigation into the Effect of Varying pH on Enzyme Activity

    The colorimeter has two knobs which can be adjusted finely to make the colorimeter read 100% transmission before the cuvettes containing the solutions are added this will be done by using the control prepared at the beginning containing protease and the milk letting it go as clear as possible (it

  1. An experiment to see the effect of pH on the activity of Catalase

    put the delivery tube in the measuring cylinder * I got the stop watch * Started the time when I pushed the mixed solution in the conical flask with the potato * Stopped the time when the gas was collected 10cm3 * Recorded my result in a table * Repeat

  2. An investigation into the effect of pH on the starch hydrolysis of fungal and ...

    These areas are expected to be circular around the holes in the agar plates. The diameters across each of the clear areas will be measured in mm using a compass. The depth of the agar will also be measured. Pilot experiment Before carrying out the investigation a pilot experiment needs

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