Question

An example for protein with quaternary structure is:

• A. Myoglobin
• B. Haemoglobin
• C. Keratin
• D. All of these

Answer 1

The correct option is B Haemoglobin

Haemoglobin has a quaternary structure which consists of four subunits. Whereas keratin is a protein with a secondary structure and myoglobin has a tertiary structure.

The primary structure refers to the linear sequence of amino acids in a polypeptide chain.
The folding of the polypeptide chain in different ways gives rise to its secondary structure like the $\alpha$-helix and $\beta$-sheets.
Tertiary structure refers to the further coiling and folding of the secondary structure upon itself in three dimensional space, like a hollow woollen ball or mass.
The quaternary structure involves the aggregation of two or more polypeptide chains or subunits in their tertiary form together in a particular fashion.