Question

The diagram of clover leaf-like structure of tRNA represent its
A. Primary Structure
B. Secondary Structure
C. Tertiary Structure
D. Quaternary Structure

Answer 1

Proteins are 3-D structures that involve the arrangement of atoms in an amino acid chain molecule. Proteins are polymers and a single amino acid monomer also called the residue. There are four levels of protein structures; primary, secondary, tertiary and quaternary.

Complete answer: According to the cloverleaf structure of tRNA, the single chain of tRNA is folded to form five arms which results in 3’ and 5’ ends that lie adjacent to each other. Each arm consists of a loop and a basal stalk. The cloverleaf structure of tRNA is actually a 2-D simplification of actual tRNA structure. The cloverleaf is therefore called the secondary structure.
a) Primary structure: It refers to the sequence of amino acids in a polypeptide chain. Peptide bonds hold the primary structure made during protein biosynthesis. Two ends of polypeptide chains are referred to as a carboxyl terminus and an amino terminus.
b) Secondary Structure: It is a highly regular structure. There are two main types of secondary structures; alpha-helix and beta-pleated sheet. These structures are defined by hydrogen bonding among them.
c) Tertiary structure: It refers to the 3-D structure of monomeric and multimeric protein molecules. It includes a compact globular structure. It has interactions like salt bridges, disulfide bonds, etc.
d) Quaternary Structure: It is a 3-D structure that consists of many subunits which function as a single functional unit. For example haemoglobin.
Hence, the correct answer is option B.

Note: The cloverleaf model of tRNA is a model which represents the molecular structure of a tRNA. It shows that a chain consists of two ends called business ends sometimes and three arms. tRNA is an adaptor molecule which is composed of RNA having 76 to 90 nucleotides in length.