Question

Choose the correct option with respect to the quaternary structure.

• A. It is the linear chain of amino acids joined together by peptide bonds.
• B. It is the folding of the polypeptide chain due to interactions among amino acids.
• C. It is the 3D structure formed due to the protein folding upon itself.
• D. It is the association of 2 or more polypeptide chains.

Answer 1

The correct option is D It is the association of 2 or more polypeptide chains.

The primary structure of a protein is the linear chain of amino acids joined together by peptide bonds. It represents the position of amino acids. There is a free -NH2 group with 𝛂- carbon at the N- terminal of the amino acid and a free -COOH group with 𝛂- carbon at the the C- terminal.
The secondary structure is the folding of the polypeptide chain due to interactions among amino acids. It can be of 2 types. 𝛂- helix resembles a spring. 𝝱- pleated sheet represents segments of polypeptide chain lining up next to each other resembling a pleated paper.
Tertiary structure is the 3D structure formed due to the protein folding upon itself. It is the biologically active form of a protein.
Quaternary structure is the association of 2 or more polypeptide chains. Each chain is considered a subunit. It is the arrangement of each folded polypeptide chain with respect to each other. Eg:- Haemoglobin has 2𝛂 and 2𝝱 chains.