What is the function of mRNA?

Appeared in: AIIMS Jodhpur SNO-2023

Explanation

Messenger RNA (mRNA) acts as a molecular courier, carrying genetic instructions from the DNA in the cell's nucleus to the ribosomes in the cytoplasm.
These instructions are encoded in three-nucleotide sequences called codons, which specify the order of amino acids in a protein.
The process of using the mRNA template to synthesize a protein is called translation.
Therefore, its fundamental role is to carry the message for protein synthesis.

Option A: This describes the function of Transfer RNA (tRNA). tRNA molecules are responsible for bringing the correct amino acids to the ribosome, matching them to the mRNA codons.
Option C: This is the role of Ribosomal RNA (rRNA). rRNA is a key structural and catalytic component of ribosomes, the cellular machinery where translation occurs.
Option D: This phrase is vague but best describes the action of enzymes like DNA polymerase or RNA polymerase during replication or transcription, where new strands are synthesized by bonding nucleotides. It is not the primary function of the completed mRNA molecule itself.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Function of Messenger RNA (mRNA) in protein synthesis as background academic context rather than a clinical decision trigger.
Understanding mRNA's function is fundamental to modern medicine, especially for the development of mRNA vaccines (e.g., for COVID-19), which provide our cells with mRNA instructions to produce a specific viral protein, thereby triggering an immune response.
Many genetic disorders, such as cystic fibrosis and sickle cell anemia, are caused by mutations in DNA that lead to faulty mRNA transcripts and, consequently, non-functional or harmful proteins.
What if? - If a mutation occurred in the DNA sequence that is transcribed into mRNA, the resulting mRNA would carry an incorrect 'message'. This could lead to the wrong amino acid being incorporated into the protein, potentially causing a disease.

How to Approach the Question

First, identify the key term in the question: 'mRNA'.
Recall the central dogma of molecular biology: DNA -> RNA -> Protein.
Focus on the role of RNA as the intermediary. The 'm' in mRNA stands for 'messenger'.
Evaluate each option based on this knowledge. The phrase 'Carries message' directly aligns with the function of a messenger molecule.
Systematically eliminate the other options by associating them with their correct molecules: 'escorts amino acid' is the job of tRNA (transfer RNA), and 'helps form the ribosomes' is the job of rRNA (ribosomal RNA).

Concept Tested & Keywords

Q5Inkmkivmdv3dumo4xLx9

E6 Physiology Guyton 4SAE Part 1 p. 58-60

E6 Pathology- ROBBINS & COTRAN PATHOLOGIC BASIS OF DISEASE 10TH Ed p. 56-60

Practise the full AIIMS Jodhpur SNO-2023

Attempt every question from this paper in a timed mock, then review the full solution for each one.