Then get beaker A and put it in the thermostatic water bath for 4 minutes, after you’ve adjusted the temperature to 35°C. Use the stop watch to time the 4 minutes. During the 4 minutes draw up a time table for your results and calculations like shown below:
When the 4 minutes has ended remove the beaker and add 5 drops of rennin solution using the pipette to the beaker and then stir with stirring rod. Restart the stop watch and put the glass slide in the beaker. Pull the slide out every 10 seconds until a fleck occurs on the slide then record the reading of the stop watch in results table.
Continue to do the same with the beakers B-F making sure the conditions e.g. same 10 second time interval are all the Same so the results will be accurate.
Afterwards Convert the times taken for first observation of coagulation into relative rates of coagulation/fleck formulation by diving 1000 by the time taken in seconds for each tube as follows:
Relative rate of fleck formation ═ 1000
t
t= time taken for fleck to appear. Add the results of your calculations to your table.
Then use the results form your results table to plot a graph showing the distribution of the relative rate of fleck formation like shown below. Presenting your data in a graph will help you draw conclusions: you can see what type of correlation there is.
Prediction
Calcium ions are required to activate rennin and rennin makes soluble milk protein caseionogen into insoluble protein paracasein. So as the concentration of calcium increases so does the activity of the enzyme.
Calcium chloride is a source of calcium ions so as the amount of calcium chloride added to the milk increases the rate of coagulation will increase because there will be more calcium ions to activate the rennin.
Sodium citrate solution removes calcium ions from milk so as the amount of citrate solution added to the milk increases the rate of coagulation will decrease because there will be less calcium ions to activate the rennin.
If calcium ions are completely removed by citrate solution (this may be done by adding 1cm³ sodium citrate solution to every 10cm³of milk) then the milk won’t coagulate because there will be no calcium ions to activate the rennin.
Remarks
All enzymes have properties of proteins because they are protein molecules so they are denatured at high temps. I decided to have the water bath at 35°C so the enzyme won’t be denatured and because rennin is an enzyme and most enzymes have an optimum temperature of about 35°-40°C.
Temperature had to be a controlled variable to keep the test fair because it affects the rate of enzyme activity. Enzyme concentration also had to be controlled to make the test fair because enzyme concentration would affect the rate of coagulation.
To see how calcium ions act as a rennin activator the concentration of calcium ions had to be varied that is why I chose the concentration of calcium ions as my independent variable.
The plan could be improved my doing repeated testing this would make the results more accurate. Could have pulled the glass slide out every 5 seconds to check for a fleck
Bibliography:
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