General Properties Of Proteins (3.1.4.1)

Question 1

What are proteins?

Answer 1

• The polymers of amino acids

Question 2

How is a peptide bond formed?

Answer 2

• Through a condensation reaction between amine group and carboxyl group, with the elimination of a water molecule

Question 3

What is the primary structure?

Answer 3

• Refers to the sequence of amino acids in the polypeptide chain

Question 4

What is the secondary structure?

Answer 4

• Represents the folding or coiling of the polypeptide chain as a result of the hydrogen bonding between amino acids
• The chain can fold into a β pleated sheet or coil into an α helix

Question 4

What is the tertiary structure?

Answer 4

• The further folding and coiling of the secondary structure due to the hydrogen, ionic and disulfide bonds and so creating a unique 3D shape

Question 5

What is the quaternary structure?

Answer 5

• When proteins consist of more than one polypeptide chain
• The polypeptide chains are held together by hydrogen, ionic and disulfide bonds

Question 6

Describe the biuret test and positive result for proteins

Answer 6

• Add biuret reagent
• A purple or lilac colour

Question 6

What is denaturation of a protein?

Answer 6

• An alteration in the tertiary structure of a protein
• The loss of 3D shape of the protein causes the protein to be no longer functional