Question

Which form of RNA has a structure resembling clover leaf?
(A) rRNA
(B) HnRNA
(C) mRNA
(D) tRNA

Answer 1

Hint: The cloverleaf model was presented by a scientist named ‘Holley’. This structure of RNA looks like a cloverleaf when observed in two dimensions whereas in a three-dimensional structure it appears L- shaped.

Complete answer:
The cloverleaf structure is a representation of tRNA. Although the structure of tRNA appears clover-like but in actual structure, the tRNA is a compact molecule which basically looks more like an inverted ‘L’. The molecule of tRNA is folded due to the folding of some complementary nitrogenous bases that come across with each other and form hydrogen bonds amongst them. The places where hydrogen bonding does not take place are known as loops. Each loop is named differently according to its function. For e.g. The Attachment loop is named because this loop connects t-RNA to the larger subunit of the ribosome. The recognition loop or anticodon loop is the most specific loop of tRNA and the types of tRNA are differentiated due to this loop. The end of this loop represents the specific sequence of three nucleotides known as Anticodon. This anticodon helps the tRNA to recognize its position on the mRNA i.e. the anticodon of tRNA recognizes its complementary sequence on mRNA which is called a codon. The third loop is known as the DHU loop which is also called the Amino – acyl synthetase recognition loop. The DHU loop plays a role in the recognition of a specific enzyme known as the Aminoacyl synthetase enzyme.

Therefore the correct option is (D) tRNA.

Note: tRNA shares 10 – 15% of the total RNA. The synthesis of tRNA takes place in the nucleus by the DNA. It is the smallest RNA and is also known as soluble RNA or Adapter RNA. The tRNA molecule is single-stranded. The cloverleaf model describes the structure that comprises two ends along with the three arms of the chains of tRNA.