12 Questions
Which of the following is a component of an amino acid?
Amino group, Carboxyl group, Hydrogen atom, R group
What color is produced when proteins and peptides react in the Biuret test?
Purple
The Biuret test primarily detects the presence of what in a sample?
Proteins or peptides
Which reagent is used in the Biuret test?
Biuret reagent
What is the principle behind the Biuret test?
Reaction of proteins and peptides with dilute copper sulfate in an alkaline solution to form a purple color
Which among the following tests gives positive results with all proteins and amino acids?
Biuret test
Which component in an amino acid is unique for each different amino acid?
R group
Which test can be used to detect proteins in a biological mixture?
Biuret test
Why does the Biuret test produce a purple color?
Reaction of peptide bonds with alkaline copper sulfate
What is the purpose of adding NaOH in the Biuret test?
To make the solution alkaline
Which of the following reagents is used in the Biuret test?
Copper sulfate solution
What does the intensity of the purple color in a Biuret test indicate?
The amount of proteins present
Study Notes
Amino Acids and Proteins
- An amino acid consists of an amino group, a carboxyl group, a hydrogen atom, and a distinctive R group bonded to a carbon atom.
Protein Detection Tests
- Color producing tests are used to detect proteins in biological mixtures.
- These tests include the Biuret, Ninhydrin, Millon's, and Hopkins - Cole tests, among others.
Biuret Test
- The Biuret test is a general test that gives a positive result with all proteins and amino acids.
- The test depends on the reaction of cupric ions (Cu+2) in an alkaline solution with peptide linkages of the protein to produce a purple color.
- Objective: detect the presence of peptides or proteins in a sample.
- Principle: Proteins and peptides form a purple color when treated with an alkaline solution of dilute copper sulfate.
- A positive test is indicated by the formation of a purple color.
- The color density is proportional to the amount of proteins present.
- Biuret reagent: alkaline copper sulfate solution.
Biuret Test Procedure
- Add 1 ml of 2% albumin (protein) to a tube.
- Add 0.5 ml of biuret reagent and mix well.
- Add 2 ml of 10% NaOH to the tube.
Amino Acids and Proteins
- An amino acid consists of an amino group, a carboxyl group, a hydrogen atom, and a distinctive R group bonded to a carbon atom.
Protein Detection Tests
- Color producing tests are used to detect proteins in biological mixtures.
- These tests include the Biuret, Ninhydrin, Millon's, and Hopkins - Cole tests, among others.
Biuret Test
- The Biuret test is a general test that gives a positive result with all proteins and amino acids.
- The test depends on the reaction of cupric ions (Cu+2) in an alkaline solution with peptide linkages of the protein to produce a purple color.
- Objective: detect the presence of peptides or proteins in a sample.
- Principle: Proteins and peptides form a purple color when treated with an alkaline solution of dilute copper sulfate.
- A positive test is indicated by the formation of a purple color.
- The color density is proportional to the amount of proteins present.
- Biuret reagent: alkaline copper sulfate solution.
Biuret Test Procedure
- Add 1 ml of 2% albumin (protein) to a tube.
- Add 0.5 ml of biuret reagent and mix well.
- Add 2 ml of 10% NaOH to the tube.
Learn about the structure of amino acids and various protein detection tests, including the Biuret test, Ninhydrin test, and more.
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