BPSC 69th CCE Prelims General Studies · Question 25 of 144

Correct — A, Messenger Ribonucleic Acid. The name describes the job. A gene is a stretch of DNA stored in the nucleus, and the ribosomes that actually build proteins sit outside it in the cytoplasm, so the instruction has to be carried across. Transcription copies one gene into a single strand of RNA; that strand leaves the nucleus, docks with a ribosome, and is read three bases at a time, each triplet or codon calling up one amino acid until a complete protein chain has been assembled. The RNA does nothing but carry the message, and is then degraded — which is why it was named the messenger. The naming is documented: Sydney Brenner and Francis Crick conceived the idea on 15 April 1960 at King's College, Cambridge, while François Jacob described the Paris experiments to them; the molecule was experimentally characterised in May 1961 in two back-to-back papers in Nature, one by Brenner, Jacob and Meselson and one by Gros and colleagues; and it was Jacob with Jacques Monod who coined the term 'messenger RNA'. The pandemic framing in the stem points at the vaccine platform that made the acronym a household word: Pfizer-BioNTech's Comirnaty and Moderna's Spikevax, first authorised in December 2020, and India's own self-amplifying GEMCOVAC-19 from Gennova Biopharmaceuticals, all work by supplying that middle step ready-made — a synthetic messenger for the SARS-CoV-2 spike protein, wrapped in a lipid nanoparticle so it survives long enough to reach a cell, which then manufactures the antigen itself. Days after this paper was sat, on 2 October 2023, Katalin Karikó and Drew Weissman were announced as winners of the Nobel Prize in Physiology or Medicine for the chemistry that made those vaccines possible.

• (b)Mutant Ribonucleic Acid — No molecule of this name exists. The option trades on a genuine confusion from the pandemic years: SARS-CoV-2's own genome is RNA, and changes in that genome are what produced the named variants — Alpha, Delta, Omicron. But that is the virus's hereditary material mutating, an entirely different thing from the cell's messenger RNA, and a mutation is an event that happens to a sequence, never a class of molecule.
• (c)Modified Ribonucleic Acid — The one distractor with a real fact behind it, and the reason a well-read candidate can talk himself out of the right answer. The mRNA inside Comirnaty and Spikevax genuinely is chemically modified — every uridine is replaced by N1-methylpseudouridine so the innate immune system does not destroy the strand on arrival — and that single modification is precisely what the 2023 Nobel Prize in Physiology or Medicine honoured. But 'm' has stood for messenger since Jacob and Monod named the molecule in 1961, six decades before nucleoside modification existed. The chemistry is real; the expansion is not.
• (d)Mnemonic Ribonucleic Acid — A pure decoy, built to be plausible to a candidate reasoning from the English word rather than the biology. 'Mnemonic' means aiding memory, and since mRNA does carry information the word can feel almost right. There is no molecule so named, and the analogy fails anyway: mRNA is a short-lived working copy that the cell destroys after use, so if anything it is the opposite of a memory device — the archive is the DNA.

The central dogma of molecular biology, set out by Francis Crick in 1958, describes the one-way flow of sequence information in a cell: DNA is replicated, transcribed into RNA, and the RNA is translated into protein. Three kinds of RNA divide the work of that last stage. Messenger RNA carries the copied instruction from gene to ribosome. Transfer RNA fetches the correct amino acid for each codon and holds the anticodon that pairs with it. Ribosomal RNA, together with proteins, builds the ribosome itself and catalyses the peptide bond. RNA differs from DNA on three structural counts — it uses the sugar ribose rather than deoxyribose, the base uracil rather than thymine, and it is usually single-stranded rather than a double helix. Eukaryotic mRNA is further processed before it leaves the nucleus: introns are spliced out, a 7-methylguanosine cap is added at the 5' end and a poly(A) tail at the 3' end, both of which protect the strand from being chewed up by enzymes. Its short life is the point — a messenger that persisted would keep making protein the cell no longer needs, so mRNA is deliberately disposable.

This is an acronym question with no reasoning route other than knowing the biology, so the useful work is in seeing why the three wrong options were chosen. All four keep 'Ribonucleic Acid' constant and vary only the first word, which tells you the examiner is testing exactly one thing: what the 'm' stands for. 'Mutant' plays on the variant news of 2021 and 2022, 'Mnemonic' on the English sense of carrying a message, and 'Modified' on a genuine technical fact about the vaccines themselves. Option (c) is the trap that actually catches people, because the mRNA in the COVID-19 vaccines really is nucleoside-modified, and a candidate who has read a little more than the syllabus can reason himself straight into it. The defence is chronological: the molecule was named in 1961, and no property of a vaccine developed in 2020 can retrospectively change what a 1961 acronym means. Anchor it to the function instead — the strand carries a message from the DNA archive in the nucleus to the ribosome, does nothing else, and is then thrown away.

• The central dogma runs DNA → RNA → protein. Transcription copies a gene into messenger RNA in the nucleus; translation at the ribosome reads that mRNA three bases at a time and assembles the corresponding chain of amino acids.
• The concept was conceived by Sydney Brenner and Francis Crick on 15 April 1960 at Cambridge and confirmed in May 1961 in two back-to-back Nature papers — Brenner, Jacob and Meselson, and Gros and colleagues. François Jacob and Jacques Monod coined the name 'messenger RNA'.
• The genetic code has 64 codons: 61 specify amino acids, AUG both starts translation and codes for methionine, and UAA, UAG and UGA terminate it. Cracking the code won Marshall Nirenberg, Robert Holley and Har Gobind Khorana — born at Raipur in undivided Punjab in 1922 and later a Padma Vibhushan — the 1968 Nobel Prize in Physiology or Medicine.
• RNA differs from DNA in three ways: ribose instead of deoxyribose, uracil instead of thymine, and a single strand instead of a double helix. Eukaryotic mRNA also carries a 5' cap and a 3' poly(A) tail that slow its degradation.
• mRNA vaccines deliver a synthetic messenger for the SARS-CoV-2 spike protein inside a lipid nanoparticle: Pfizer-BioNTech's Comirnaty and Moderna's Spikevax were first authorised in December 2020, and India's self-amplifying GEMCOVAC-19 from Gennova Biopharmaceuticals followed. Katalin Karikó and Drew Weissman were announced as 2023 Nobel laureates in Physiology or Medicine on 2 October 2023 for the nucleoside modification that made the platform work.

• Choosing 'Modified' because the mRNA in the COVID-19 vaccines truly is nucleoside-modified — the acronym predates that chemistry by six decades
• Confusing messenger RNA with a virus's RNA genome; SARS-CoV-2 does store its genes in RNA, but that is hereditary material, not a cellular messenger
• Mixing mRNA up with transfer RNA and ribosomal RNA, which work in the same process but fetch amino acids and form the ribosome respectively

BPSC asks scientific acronyms straight, wrapped in a current-affairs cue — this paper also asks for the full form of GPT in ChatGPT, and on the 71st CCE it asked for the full form of the biodegradable polymer PHBV, with all the wrong options built from real-sounding chemistry. UPSC almost never asks a bare expansion. It asks what a term denotes instead — 'transcriptome' as the full range of mRNA molecules an organism expresses (2016) — or which platform a named vaccine uses (2022), or what an RNA-based technology can actually do (RNA interference, 2019). Learn the expansion for BPSC and the function for UPSC.

• practice — not a real PYQ

  In the process of protein synthesis, messenger RNA performs which one of the following functions?

  • (a)It carries the coded instruction from the DNA to the ribosome
  • (b)It brings the specific amino acid to the site of protein synthesis
  • (c)It forms the structural core of the ribosome itself
  • (d)It supplies the energy required to link two amino acids

  Answer(a) It carries the coded instruction from the DNA to the ribosome — precisely what makes it the 'messenger'. Fetching the amino acid in (b) is the work of transfer RNA, the ribosome's core in (c) is built by ribosomal RNA, and the energy in (d) comes from ATP and GTP.

• practice — not a real PYQ

  Consider the following statements about RNA: 1. It contains the sugar ribose in place of deoxyribose. 2. It contains the base uracil in place of thymine. Which of the statements given above is/are correct?

  • (a)1 only
  • (b)2 only
  • (c)Both 1 and 2
  • (d)Neither 1 nor 2

  Answer(c) Both 1 and 2 — RNA is built on ribose and uses uracil wherever DNA uses thymine. A third difference worth remembering is that RNA is usually single-stranded, while DNA is a double helix.