What is the function of mRNA?

AIIMS Jodhpur SNO-2023

Pathology & Genetics

Easy

Appeared in: AIIMS Jodhpur SNO-2023

Explanation

Messenger RNA (mRNA) acts as the intermediary molecule in protein synthesis.
It carries the genetic instructions, transcribed from a DNA template in the nucleus, to the protein-making machinery in the cytoplasm.
The sequence of nucleotides in mRNA, organized into codons, dictates the specific sequence of amino acids in the resulting protein.
This process of reading the mRNA to build a protein is called translation.

Option A: This describes the function of Transfer RNA (tRNA), not mRNA. Each tRNA molecule is specific to one amino acid and has an anticodon that pairs with a corresponding codon on the mRNA strand.
Option C: This is the primary role of Ribosomal RNA (rRNA). rRNA combines with proteins to form the two subunits of a ribosome, which is the site of protein synthesis.
Option D: This phrase is vague but most accurately describes the action of DNA polymerase during DNA replication (where it bonds nucleotides to form a new DNA strand) or RNA polymerase during transcription (forming an RNA strand). It is not the primary function of the completed mRNA molecule.

Visual 1: Diagram - The Central Dogma of Molecular Biology. A flowchart showing the flow of genetic information: DNA → (transcription) → RNA → (translation) → Protein. This visual clearly places mRNA as the key link between DNA and protein.
Visual 2: Illustration - Protein Synthesis. A detailed image showing an mRNA strand moving through a ribosome, with tRNA molecules bringing amino acids to be added to the growing polypeptide chain. This helps visualize the interaction between all three major types of RNA.

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 function is fundamental to modern medicine, particularly in vaccine development. mRNA vaccines (e.g., for COVID-19) work by introducing a synthetic mRNA sequence that instructs the body's cells to produce a specific viral protein, triggering an immune response without causing illness.
Many genetic diseases are caused by mutations in DNA that lead to faulty mRNA and, consequently, non-functional or harmful proteins. Gene therapies often target the correction of these mRNA messages.
What if? - If a mutation occurred in the 'stop' codon of an mRNA sequence, translation would continue past the normal endpoint, resulting in an abnormally long and likely non-functional protein. This can lead to various cellular dysfunctions and diseases.

How to Approach the Question

First, identify the core subject of the question, which is 'mRNA'.
Recall the central dogma of molecular biology: DNA makes RNA, and RNA makes protein. This helps frame the roles of different molecules.
Differentiate the functions of the three main types of RNA: mRNA (the 'message'), tRNA (the 'transporter'), and rRNA (the 'ribosome factory').
Evaluate each option against these defined roles. 'Carries message for protein synthesis' directly matches the known function of mRNA.
Eliminate the other options by correctly assigning their functions to tRNA and rRNA, or by recognizing that they describe a different biological process.

Concept Tested & Keywords

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