Question

Match the level of organization in structure of protein (Column I) with its feature/type of folding (Column II) and functional status (Column III):

• A. $$\begin{array}{ccc}\text{Column I}& \text{Column II}& \text{Column III}\\ \text{Primary Structure}& \text{Linear sequence of amino acids}& \text{Functional}\end{array}$$
• B. $$\begin{array}{ccc}\text{Column I}& \text{Column II}& \text{Column III}\\ \text{Secondary structure}& \text{Helix or plate form}& \text{Functional}\end{array}$$
• C. $$\begin{array}{ccc}\text{Column I}& \text{Column II}& \text{Column III}\\ \text{Tertiary Structure}& \text{Hollow wollen ball}& \text{Non-functional}\end{array}$$
• D. $$\begin{array}{ccc}\text{Column I}& \text{Column II}& \text{Column III}\\ \text{Quaternary structure}& \text{2 or more polypeptide chains arranged}& \text{Functional}\end{array}$$

Answer 1

The correct option is D $$\begin{array}{ccc}\text{Column I}& \text{Column II}& \text{Column III}\\ \text{Quaternary structure}& \text{2 or more polypeptide chains arranged}& \text{Functional}\end{array}$$

The sequence of amino acids i.e., the positional information in a protein – which is the first amino acid, which is second, and so on – is called the primary structure of a protein. A protein is imagined as a line, the left end represented by the first amino acid and the right end represented by the last amino acid. The primary structure of a protein is non-functional.

Some portions of the amino acid chain are arranged in the form of a helix or sheets or plates which is called the secondary structure. The secondary structure of a protein is also non-functional.

In addition, the secondary structure is also folded upon itself like a hollow woolen ball, giving rise to the tertiary structure. This gives a 3-dimensional view of a protein. Tertiary structure is absolutely necessary for the many functional activities of proteins.

Some proteins are an assembly of more than one polypeptide or subunits. The manner in which these individual polypeptides or subunits are arranged with respect to each other is the architecture of a protein otherwise called the quaternary structure of a protein. Quaternary structure is necessary for its function.