Assignment Flashcards
Aim
To investigate the effect of hydrogen peroxide concentration on potato catalase activity
Underlying Biology: Inhibitors
Inhibitors are molecules that bind to enzymes in order to make it less likely for a substrate to bind to the active site; resulting in a decrease in enzyme activity. There are three types of inhibitors- competitive, non-competitive and feedback.
Underlying Biology: Competitive Inhibitors
Competitive inhibitors are a similar shape to the substrate, they compete with the substrate to bind to the active site; if they’re successful it causes enzyme activity to decrease as the substrate will be unable to bind to the enzyme
Underlying Biology: Non-competitive Inhibitors
Non-competitive inhibitors bind away from the enzymes active site which stops the substrate from binding as it causes the enzyme’s active site to change shape. This means that there will be a decrease in enzyme activity as the substrate will no longer be able to bind to the active site.
Underlying Biology: Reversible/Non-reversible
The effect of competitive inhibitors can be reversed by increasing substrate concentration as it increases the chance of substrate binding to the active site, therefore increasing the enzyme activity. The effect of non-competitive inhibitors can’t be reversed by increasing the concentration of substrate as by changing the shape of the active site it prevents any reaction from taking place, decreasing enzyme activity.
Method
Potato is cored and cut into equal pieces with a ruler and scalpel. Measured hydrogen peroxide of different concentrations are syringed into separate boiling tubes. Equal drops of detergent are added to each tube with a dropper. One potato is added to each tube and the time is recorded with a stopwatch. After 5 minutes, the height of foam is recorded with a ruler. The experiment is then repeated with the same range of concentrations.
Analysis
My results indicate that as the substrate concentration increases, the average height of foam also increases. An increase in the height of foam means there’s an increase in enzyme activity. In the second source, the substrate concentration also increases which causes the rate of enzyme activity to increase, however at a certain point the rate of enzyme activity levels out. As my second source has no values, I cannot compare any similarities or differences between the range of values used
Conclusion
In conclusion, as the substrate concentration is increased the rate of enzyme activity also increases until a certain point. This can be seen as the height of foam increases as the hydrogen peroxide concentration increases. The greater the height of foam produced, the greater the enzyme activity.
Evaluation: Temperature
Temperature was not kept constant, which may have made the results less valid as temperature affects enzyme activity. I could’ve managed this by using water baths set at specific temperatures.
Evaluation: Similar Results
I think that the results I gathered from my experiment were reliable as my height of foam produced at each concentration were similar in all the repeats carried out.
Evaluation: Dropping Potatoes
The potatoes couldn’t be dropped into each boiling tube at the exact same time, which may have made the results less accurate as some potatoes will have had more time to react with the substrate than the others.
