Practical 1 Flashcards
Investigation into the effect of a named variable on the rate of an enzyme-controlled reaction.
The effect of temperature on the rate of the reaction catalysed by trypsin. Casein is a protein found in milk. Trypsin is an enzyme that digests casein. When trypsin is added to a dilute solution of milk powder, the casein is digested and the solution goes clear.
You will test one temperature. You will obtain additional results from other students in your class for 4 other temperatures.
1 You used a buffer in your investigation. Explain why buffer solutions are used
Maintain constant pH; 1
Casein is a protein found in milk. Trypsin is an enzyme that digests casein. When trypsin is added to a dilute solution of milk powder, the casein is digested and the solution goes clear.
You will test one temperature. You will obtain additional results from other students in your class for 4 other temperatures.
You left the test tubes in the water bath for 10 minutes before you added the enzyme to the milk powder solutions. Explain why you did this.
To equilibrate/reach temperature at which reaction will take place; 1
Casein is a protein found in milk. Trypsin is an enzyme that digests casein. When trypsin is added to a dilute solution of milk powder, the casein is digested and the solution goes clear.
You will test one temperature. You will obtain additional results from other students in your class for 4 other temperatures.
3 Describe and explain what you did to make sure the temperatures of the water baths were as reliable as possible.
Measure temperature (several times) and add hot or cold water as appropriate;
at regular intervals
To try to keep the temperature close to that required;
Investigation into the effect of a named variable on the rate of an enzyme-controlled reaction.
The effect of temperature on the rate of the reaction catalysed by trypsin.
Casein is a protein found in milk. Trypsin is an enzyme that digests casein. When trypsin is added to a dilute solution of milk powder, the casein is digested and the solution goes clear.
You will test one temperature. You will obtain additional results from other students in your class for 4 other temperatures
.Explain why you set up three experiments at each temperature.
Enables calculation of a more reliable mean; So that anomalous data can be identified; 2
Investigation into the effect of a named variable on the rate of an enzyme-controlled reaction.
The effect of temperature on the rate of the reaction catalysed by trypsin.Casein is a protein found in milk. Trypsin is an enzyme that digests casein. When trypsin is added to a dilute solution of milk powder, the casein is digested and the solution goes clear.
A student decided to improve this investigation with control experiments. At each temperature she set up a test tube containing a solution of milk powder and buffer. She did not add trypsin. What would these control experiments show? [CPAC 2c] (1)
Controls show that the casein digested was due to the action of enzyme / not due to temperature changes;
Investigation into the effect of a named variable on the rate of an enzyme-controlled reaction.
The effect of temperature on the rate of the reaction catalysed by trypsin.Casein is a protein found in milk. Trypsin is an enzyme that digests casein. When trypsin is added to a dilute solution of milk powder, the casein is digested and the solution goes clear.
Suggest a more appropriate control for this enzyme controlled investigation.
Boiled trypsin; 1
makesthe ezymes denatured no longer colour change
GRAPH SHOWING RATE OF REACTION ((y) AGAINST TEMPRETURE. (x)
DESCRIPTION: RATE OF REACTION INCREASES TILL 40 AND PEAKS AT 40 THE SUDDENLY DECREASES RATE OF REACTION. explain the results in context of enzyme and temperature and rate of reaction (5)
- As temperature increases there is an increase in kinetic energy / speed of molecules; 2. More/greater probability of collisions between active site and substrate / greater number of E-S complexes formed; 3. Above optimum/40 °C denaturation of enzyme occurs; 4. Change in tertiary structure/shape of active site; 5. Due to breaking of hydrogen bonds; 6. Fewer E-S complexes formed;
Investigation into the effect of a named variable on the rate of an enzyme-controlled reaction.
The effect of temperature on the rate of the reaction catalysed by trypsin.Casein is a protein found in milk. Trypsin is an enzyme that digests casein. When trypsin is added to a dilute solution of milk powder, the casein is digested and the solution goes clear.It is difficult to decide when the solution of milk powder goes clear. Suggest one better way of determining when the solution of milk powder goes clear. Give 2 ways
Use a colorimeter; Record time taken to reach constant/set value (of absorbance / transmission);
OR Set up a standard / solution where complete digestion has occurred for comparison; Measure the time taken to reach same colour/transparency as standard; (2)
Investigation into the effect of a named variable on the rate of an enzyme-controlled reaction.
The effect of temperature on the rate of the reaction catalysed by trypsin. Casein is a protein found in milk. Trypsin is an enzyme that digests casein. When trypsin is added to a dilute solution of milk powder, the casein is digested and the solution goes clear.
You will test one temperature. You will obtain additional results from other students in your class for 4 other temperatures.Decscribe how you can change the method to make it more reliable. 1
Carry out at least 5 repeats and calculate a mean/average;
Investigation into the effect of a named variable on the rate of an enzyme-controlled reaction.
The effect of temperature on the rate of the reaction catalysed by trypsin. Casein is a protein found in milk. Trypsin is an enzyme that digests casein. When trypsin is added to a dilute solution of milk powder, the casein is digested and the solution goes clear.
You will test one temperature. You will obtain additional results from other students in your class for 4 other temperatures.
In this experiment you controlled the temperature of the water bath. List 2 other variables you controlled in this investigation.
Concentration of enzyme; Concentration of substrate; pH; Accept: Volume of substrate/enzyme
how is rate of reaction calculated from time
rate of reaction = 1/ time
