An experiment was carried out by the student to investigate the ability of reducing sugars to diffuse through Visking tubing. Fig. 6.2 shows the apparatus used.
Fig. 6.2
At the start of the experiment, the external solution did not contain any reducing sugars.
At intervals, the student tested for the presence of reducing sugars, both within the Visking tubing and in the external solution.
Name the reagent that is used to test for the presence of reducing sugars.
Glucose is used in the synthesis of amylose. Glucose is first converted to glucose 1-phosphate (G 1-P).
Starch phosphorylase is an intracellular enzyme that can catalyse the synthesis of amylose from G 1-P, which is the substrate for the reaction:
n= a large number
Students used a colorimeter to investigate the progress of the reaction.
The students made a reaction mixture containing 1-P in a buffer solution at pH6.0. A very small quantity of amylose was added to initiate the reaction.
A solution of starch phosphorylase was added to the reaction mixture and samples were taken at 1-minute intervals. Each sample was added to a dilute iodine solution, stirred and then poured into a cuvette. The absorbance of each solution was recorded.
The results of the investigation are shown in Fig. 2.1.
Fig. 2.1
Explain why the absorbance increases, as shown in Fig. 2.1.
Lipase is an enzyme with many commercial uses. Some species of bacteria are of great interest as they produce large quantities of lipase.
To measure the activity of the bacterial lipase during their investigations, the researchers used a method based on the biological test for triglycerides.
Outline a biological test that could be carried out to show the presence of triglyceride in a liquid mixture and describe the positive result for this test.