Tests for biological molecules Flashcards
What is used to test for reducing sugars?
Benedict’s reagent
What are reducing sugars?
Sugars that can donate electrons to reduce other molecules
What is a positive result for reducing sugars?
Red is high concentration, green is low concentration
What is colorimetry used for?
To calculate reducing sugar concentration in a sample
Why is blue light reflected and red light absorbed?
The lower the concentration of reducing sugar, the higher the amount of unreacted copper sulphate so it is more blue
What can a calibration curve be used for?
To determine unknown concentrations of the glucose in a solution.
What is another way of testing for reducing sugars?
Test strips compared to a calibration card
How are non-reducing sugars tested for?
They do not change the colour of Benedict’s, so HCl must be added first and heated
What is iodine used for?
To test for the presence of starch
What is a positive starch test result?
Colour change form yellow-brown to blue-black
What is the test for proteins?
Biuret test (detects peptide bonds)
What is a positive Biuret test result?
Light blue to purple solution
What is used to test for lipids?
Emulsion test
What is a positive result for lipids?
Cloudy white emulsion forming (lipids are insoluble in water)
When are biosensors used?
To test for water contaminants or food toxins
