Enzyme Investigation. How to find the best concentration of hydrogen peroxide that will react with the catalyse enzyme source the best? How to find the best PH buffer for the reaction to take place?

Authors Avatar

Enzyme investigation

Introduction: An enzyme is a biological catalyst used in our body’s to speed up chemical reactions, in our case the enzyme was catalase and act by breaking up the hydrogen peroxide source. There are a variety of different chemicals or aspects that can affect the productivity of the enzyme for example the saturation point; this is the point where the reaction involving the enzyme slows right down to a stop and can occur if the enzyme denatures usually by heat. There are always a lot of potential variables but we tried to control them as much as we possible, only changing the independent variable looking at the effect of this change on the dependent variable. After this, the results showed the predicted effect allowing us to form a conclusion and right any noticeable patterns or unexpected outcomes.

Aim: How to find the best concentration of hydrogen peroxide that will react with the catalyse enzyme source the best? How to find the best PH buffer for the reaction to take place?

Pre-test equipment:

  • Gas syringe- to measure the oxygen to the nearest cm³ (dependent variable) the oxygen produced was the outcome that we decided to look at to see what was the best concentration this changed for every different concentration.
  • Delivery tube- to let the oxygen pass through into the gas syringe
  • Conical flask- to hold the substances
  • Hydrogen peroxide(10 volume)-to react with the catalyse (controlled variable) we measured out the same volume of hydrogen peroxide only changing the amount mixed with the water leading to a fair test with reliable results.
  • Balance- to weigh the liver to the nearest hundredth of a gram
  • Weighing boat- to hold the liver on the balance
  • Liver- source of catalase (controlled variable) we weighed this out trying to get as close to 1 gram as possible to the nearest hundredth of a gram we gave an error bar of 0.03 of a gram different either way this resulted in a very accurate and controlled test and results.
  • White tile- to cut the liver on
  • Scalpel- to cut the liver with
  • Stop clock- to time the reaction
  • Clamp- to hold the gas syringe
  • Goggles- to protect your eyes
  • PH buffer, 4, 5, 6, 7, 8, 9- to se which works best in the reaction (independent variable) we changed these by testing different pH levels but kept the volume of it the same keeping a fair reliable test and accurate results.
  • 2 Measuring cylinders- to measure the substances accurately to the nearest cm³
  • Retort stand- to clamp the clamps to the gas syringe

Health and safety:

  1. Take your blazer off and hang out of the way
  2. Tie long hair back
  3. Put goggles on
  4. Stack your stools at the back of the classroom out of the way
  5. Move all of the paper and objects from the desk to the side
  6. Do not rush or run around near the experiment

How to Keep a Fair Test

  • Keep mass of liver the same (1.5 grams)
  • Use same amount of pH buffer in each experiment (5ml)
  • Keep experiment at the same temperature-this will be room temperature (rate of reaction will change at different temperatures)
  • Use same volume of hydrogen peroxide.
  • Keep the surface area of the liver the same.

All of these factors will be kept the same; the only thing that will be altered will be the independent variable, the pH level.

Pre-test aim: What is the optimum PH buffer of mix with hydrogen peroxide?

Hypothesis: The best pH buffer should be PH8 as I have research and found out that the best PH for this reaction is PH 7.6. I believe this after looking at a variety of sources such as; The Biological Science Books 1 and 2 by Green, Stout and Taylor and our science teacher Mrs Howard.

Pre-test method:

  1. Collect all of the equipment
  2. Clamp the clamp to the retort stand to clamp the gas syringe
  3. Attach the delivery tube to the gas syringe
  4. Measure out 20cm³ of hydrogen peroxide in the measuring cylinder, nearest ml (controlled variable)
  5. Measure out 5cm³ of PH buffer 4 (independent variable)
  6. Mix in the conical flask with the hydrogen peroxide (controlled variable)
  7. Cut and measure to the nearest hundredth of a gram out 1.5 grams of liver (controlled variable)
  8. Tip the liver into the conical flask
  9. Quickly time as soon  as possible after mixing them all together put the delivery tube bung in the top of the conical flask
  10. Wait 90 seconds to let the reaction start
  11. Restart the stop clock and record the oxygen produced every 30 seconds for 4 minutes
  12. Repeat twice with the same PH buffer (dependent variable)
  13. Repeat thrice with all of the other different PH buffers (dependent variable)
  14. Clean your desk and put all of your equipment away and wash your hands
Join now!

Results for pre-test:

        

Conclusion:

The results show that PH 9 was the optimum ph for the enzyme activity but after looking at a variety of sources such as The Biological science book 1 and 2 by green, stout and Taylor and our science teacher Mrs Howard we decided to use the ph 8 as we found out that the optimum PH level for this reaction was ph 7.6. After the pre-test results we decided to use a higher concentration of hydrogen peroxide going from a concentration ...

This is a preview of the whole essay