What is the structural configuration of Transfer RNA (tRNA)?

AIIMS CRE, SNO-2024

Biochemistry & Nutrition

Easy

Appeared in: AIIMS CRE, SNO-2024

Explanation

Transfer RNA (tRNA) is fundamentally a single-stranded ribonucleic acid molecule.
This single polynucleotide chain folds back on itself through complementary base pairing (A-U, G-C), creating localized double-stranded regions.
This folding results in a characteristic secondary structure known as a 'cloverleaf' and a functional tertiary 'L-shape' structure.
The primary role of tRNA is to act as an 'adapter' in protein synthesis, carrying a specific amino acid to the ribosome to be added to the growing polypeptide chain.

Option A: This describes the typical helical structure of DNA, which is composed of two separate polynucleotide chains. While tRNA has double-stranded regions from folding, the molecule itself is a single chain.
Option C: A triple helix is a rare nucleic acid structure involving three intertwined strands. This is not the configuration of tRNA.
Option D: This structure is characteristic of bacterial plasmids and the genomes of some viruses. tRNA is a linear molecule that folds; it is not a closed loop.

Visual 1: Diagram: The three levels of tRNA structure. This visual should clearly show: 1) The primary structure as a linear sequence of nucleotides. 2) The secondary 'cloverleaf' structure with its distinct arms (acceptor arm, anticodon loop, D arm, TψC arm). 3) The tertiary 'L-shaped' structure, which is the functional form in the cell.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Structural configuration of Transfer RNA (tRNA) as background academic context rather than a clinical decision trigger.
tRNA is essential for protein synthesis, which is fundamental to all cellular life. Without functional tRNA, cells cannot produce the proteins needed for structure, function, and regulation, leading to cell death.
The unique structure of bacterial tRNA and ribosomes is a key target for antibiotics. Drugs like tetracyclines and macrolides specifically inhibit bacterial protein synthesis by interfering with tRNA function at the ribosome, without harming human cells.
What if? If a mutation occurred in the gene for a specific tRNA, altering its anticodon loop, it could lead to misreading the genetic code. This would cause the wrong amino acid to be inserted into proteins, potentially leading to misfolded, non-functional proteins and disease.

How to Approach the Question

First, identify the core subject of the question, which is the fundamental structure of Transfer RNA (tRNA).
Recall the basic properties of the major nucleic acids: DNA is typically double-stranded, whereas RNA is synthesized as a single strand.
Consider the specific case of tRNA. Although it has a complex, folded shape, this three-dimensional structure arises from a single, continuous chain of nucleotides folding back on itself.
Evaluate the options based on this primary characteristic. 'Single stranded' accurately describes the fundamental nature of the molecule.
Eliminate the other options by associating them with the correct molecules: 'Double stranded' with DNA, and 'Circular' with plasmids or certain viral genomes.

Concept Tested & Keywords

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