Bio Molecules Experiments

Question 1

Describe how to test for proteins

Answer 1

Biuret test can confirm the presence of peptide bonds

Add a droplet of sodium hydroxide to the sample at room temp
Then add a dilute copper sulfate solution
Swirl

Blue -purple = protein
Blue = no proteib

Question 2

How to test for lipids

Answer 2

Milky emulsion test

Dissolve the solution in ethanol, add an equal volume of water
Shake

If a milky white emulsion appears = lipids

Question 3

How to test for reducing sugars

Answer 3

Add an equal volume of benedicts reagent to each test tube with the sample in, then heat in a water bath for 5 minutes
If the solution turns from blue to orange orthen to a red brick pigment shows that reducing sugars are present

Question 4

How to test for non reducing sugars

Answer 4

Add a hydrochloric acid to the sample then heat in water and heat in a wter bath thats been brought to boil

Neutralise the solution with sodium hydrogencarbonate
Then carry out benedicts reagent like normal