Biochemical Tests: Proteins

Question 1

What is the test for proteins

Answer 1

biuret test

Question 2

A liquid solution of a sample is treated with ……………………………. to make the solution alkaline

Answer 2

sodium or potassium hydroxide

Question 3

A few drops of copper (II) sulfate solution (which is blue) is added to the sample
Biuret ‘reagent’ contains an

Answer 3

acidic and copper (II) sulfate

Question 4

If the test is positive for a protein what colour will the solution turn

Answer 4

blue to purple

Question 5

If no colour change is observed, no protein is present

For this test to work, there must be at least ……… peptide bonds present in any protein molecules, so if the sample contains …………… the result will be negative

Answer 5

2

amino acids or dipeptides,

Question 6

The Biuret test is qualitative -

why is this

Answer 6

it does not give a quantitative value as to the amount of protein present in a sample

Question 7

qualitative meaning

Answer 7

Indicates if substance is present or not