Structure of RNA MCQs With Answer

Structure of RNA MCQs With Answer

by

Structure of RNA MCQs With Answer is a concise, student-friendly introduction designed for B. Pharm learners to master RNA architecture and its pharmaceutical relevance. This resource covers primary, secondary and tertiary motifs—nucleotides, ribose-phosphate backbone, base pairing, hairpins, bulges, pseudoknots, and modified bases—plus functional RNAs like mRNA, tRNA, rRNA, snRNA, siRNA and miRNA. Emphasis is placed on stability, enzymatic degradation, chemical modifications, and therapeutic applications such as antisense and siRNA drugs. Clear explanations and targeted questions help reinforce structural concepts crucial for drug design and biotechnology. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the basic monomer unit of RNA?

  • A ribonucleotide composed of a ribose sugar, phosphate group and nitrogenous base
  • A deoxyribonucleotide composed of deoxyribose, phosphate and base
  • A peptide formed from amino acids
  • A monosaccharide linked to an amino group

Correct Answer: A ribonucleotide composed of a ribose sugar, phosphate group and nitrogenous base

Q2. Which nitrogenous base is present in RNA but not in DNA?

  • Thymine
  • Uracil
  • Adenine
  • Cytosine

Correct Answer: Uracil

Q3. Which sugar is found in RNA nucleotides?

  • Deoxyribose
  • Fructose
  • Ribose
  • Glucose

Correct Answer: Ribose

Q4. What type of bond links adjacent nucleotides in an RNA strand?

  • Hydrogen bond
  • Peptide bond
  • Phosphodiester bond
  • Glycosidic bond

Correct Answer: Phosphodiester bond

Q5. RNA typically exists as which form in cells?

  • Double helix identical to DNA
  • Single-stranded molecule that folds into complex structures
  • Linear double-stranded polymer with thymine
  • Protein-like folded polypeptide

Correct Answer: Single-stranded molecule that folds into complex structures

Q6. What is a hairpin (stem-loop) in RNA structure?

  • A region where RNA forms a triple helix
  • A local structure formed by intramolecular base pairing creating a double-stranded stem and loop
  • A covalent crosslink between two RNA strands
  • RNA bound to protein forming a ribonucleoprotein

Correct Answer: A local structure formed by intramolecular base pairing creating a double-stranded stem and loop

Q7. Which base pair is canonical in RNA secondary structure?

  • G–T
  • A–U
  • A–T
  • C–T

Correct Answer: A–U

Q8. Which of the following is a non-Watson-Crick interaction important in RNA structure?

  • G–C Watson-Crick only
  • Hoogsteen and wobble base pairs such as G–U
  • Amino acid side chain interactions
  • Disulfide bond formation

Correct Answer: Hoogsteen and wobble base pairs such as G–U

Q9. What is a pseudoknot in RNA?

  • A protein-induced RNA cleavage site
  • A tertiary interaction where bases in a loop pair with a sequence outside the loop forming knot-like topology
  • A linear unpaired RNA region
  • An RNA bound to DNA forming R-loops

Correct Answer: A tertiary interaction where bases in a loop pair with a sequence outside the loop forming knot-like topology

Q10. Which RNA type serves as the adaptor that translates mRNA codons into amino acids?

  • mRNA
  • rRNA
  • tRNA
  • snRNA

Correct Answer: tRNA

Q11. What chemical modification is commonly found at the 5′ end of eukaryotic mRNA?

  • 5′ triphosphate only
  • 5′ cap: 7-methylguanosine (m7G) cap
  • Polyadenylation at 5′ end
  • Uridylation at 5′ end

Correct Answer: 5′ cap: 7-methylguanosine (m7G) cap

Q12. What is the primary role of rRNA in the ribosome?

  • Store genetic information
  • Provide the catalytic and structural core for protein synthesis
  • Carry amino acids
  • Degrade mRNA

Correct Answer: Provide the catalytic and structural core for protein synthesis

Q13. Which structural feature of tRNA is key for recognition by aminoacyl-tRNA synthetases?

  • Poly(A) tail
  • Anticodon loop and acceptor stem identity elements
  • 5′ cap structure
  • Promoter sequences

Correct Answer: Anticodon loop and acceptor stem identity elements

Q14. What causes RNA to be generally less stable than DNA?

  • Presence of 2′-hydroxyl group on ribose susceptible to base-catalyzed hydrolysis
  • Lack of phosphate backbone
  • Thymine residues cause instability
  • Double-stranded nature increases degradation

Correct Answer: Presence of 2′-hydroxyl group on ribose susceptible to base-catalyzed hydrolysis

Q15. Which enzyme specifically degrades RNA?

  • DNase
  • Protease
  • RNase
  • Ligase

Correct Answer: RNase

Q16. Methylation at which position of tRNA bases often affects codon recognition and stability?

  • 5′ phosphate methylation only
  • Base methylation such as N1-methyladenosine or 5-methylcytosine
  • Acetylation of ribose
  • Formylation of guanine

Correct Answer: Base methylation such as N1-methyladenosine or 5-methylcytosine

Q17. What is the function of small interfering RNA (siRNA) in cells?

  • Stimulate protein translation
  • Guide sequence-specific degradation of target mRNA via RNAi pathway
  • Form ribosomal subunits
  • Act as primers for DNA replication

Correct Answer: Guide sequence-specific degradation of target mRNA via RNAi pathway

Q18. Which technique is used to determine RNA secondary structure experimentally?

  • Mass spectrometry only
  • Hydroxyl radical or SHAPE chemical probing plus sequencing
  • Northern blot without probes
  • Western blot

Correct Answer: Hydroxyl radical or SHAPE chemical probing plus sequencing

Q19. What is the typical effect of forming a G-quadruplex in RNA?

  • Increases translation efficiency universally
  • Stabilizes certain regions and can regulate translation or splicing
  • Causes immediate degradation by RNase H
  • Prevents RNA from binding proteins

Correct Answer: Stabilizes certain regions and can regulate translation or splicing

Q20. Which part of mRNA interacts with the ribosome to initiate translation in eukaryotes?

  • 5′ untranslated region (5′ UTR) and 5′ cap
  • Poly(A) tail only
  • Introns
  • Promoter

Correct Answer: 5′ untranslated region (5′ UTR) and 5′ cap

Q21. What is an antisense oligonucleotide therapy targeting RNA?

  • A small molecule that intercalates into DNA
  • A complementary RNA/DNA oligo that binds target mRNA to modulate expression or splicing
  • An antibody against RNA polymerase
  • A lipid that fuses with membranes

Correct Answer: A complementary RNA/DNA oligo that binds target mRNA to modulate expression or splicing

Q22. Which RNA structural motif is most important for ribozyme catalytic activity?

  • Single-stranded poly(A) only
  • Specific tertiary folds bringing catalytic residues together
  • 5′ cap structures
  • Signal peptides

Correct Answer: Specific tertiary folds bringing catalytic residues together

Q23. What defines the primary structure of RNA?

  • Three-dimensional folding of RNA
  • Sequence of nucleotides linked by phosphodiester bonds
  • Pattern of hydrogen bonds in stems and loops
  • Association with ribosomal proteins

Correct Answer: Sequence of nucleotides linked by phosphodiester bonds

Q24. What does the melting temperature (Tm) of an RNA duplex indicate?

  • Temperature at which RNA polymerase is active
  • Temperature at which 50% of the duplexes are denatured into single strands
  • Temperature of maximum catalytic activity for RNases
  • Temperature at which ribosomes dissociate from mRNA

Correct Answer: Temperature at which 50% of the duplexes are denatured into single strands

Q25. Which of the following RNA species is involved in mRNA splicing in eukaryotes?

  • siRNA
  • snRNA (small nuclear RNA) within the spliceosome
  • rRNA
  • tRNA

Correct Answer: snRNA (small nuclear RNA) within the spliceosome

Q26. What is an RNA aptamer?

  • An RNA fragment that acts as an enzyme to cleave proteins
  • An RNA sequence selected to bind specific ligands with high affinity
  • A region of mRNA that codes for signal peptides
  • A misfolded RNA targeted for degradation

Correct Answer: An RNA sequence selected to bind specific ligands with high affinity

Q27. Which chemical modification is characteristic of the 3′ end of most eukaryotic mRNAs?

  • 3′ cap
  • Polyadenylation (poly(A) tail)
  • Uracil methylation
  • 5′ phosphorylation

Correct Answer: Polyadenylation (poly(A) tail)

Q28. Which structural element of tRNA forms the acceptor stem?

  • Anticodon loop
  • Base-paired 7–9 nucleotide stem at the 3′ and 5′ ends ending with CCA at 3′ terminus
  • Poly(A) tail
  • 5′ cap

Correct Answer: Base-paired 7–9 nucleotide stem at the 3′ and 5′ ends ending with CCA at 3′ terminus

Q29. Which factor most directly stabilizes RNA tertiary structure in cells?

  • High concentrations of proteases
  • Metal ions (e.g., Mg2+) and RNA-binding proteins
  • Low ionic strength and absence of cations
  • Free radicals

Correct Answer: Metal ions (e.g., Mg2+) and RNA-binding proteins

Q30. What role do RNase H enzymes play in molecular biology?

  • They degrade single-stranded RNA only
  • They cleave the RNA strand of RNA–DNA hybrids
  • They synthesize complementary DNA from RNA
  • They methylate RNA bases

Correct Answer: They cleave the RNA strand of RNA–DNA hybrids

Q31. Which experimental method converts RNA into complementary DNA (cDNA) for analysis?

  • Southern blot
  • Reverse transcription using reverse transcriptase
  • Edman degradation
  • Chromatography

Correct Answer: Reverse transcription using reverse transcriptase

Q32. In RNA, what is a bulge?

  • A fully paired double helix region
  • An unpaired nucleotide or nucleotides interrupting a helical stem
  • A covalent crosslink to protein
  • A polyadenylated sequence

Correct Answer: An unpaired nucleotide or nucleotides interrupting a helical stem

Q33. Which base-pairing interaction is known as a wobble pair in RNA?

  • A–U only
  • G–U pairing
  • A–T pairing
  • C–G only

Correct Answer: G–U pairing

Q34. Which of the following RNAs is typically involved in gene silencing and post-transcriptional regulation?

  • mRNA only
  • miRNA (microRNA)
  • rRNA only
  • tRNA only

Correct Answer: miRNA (microRNA)

Q35. What is the pharmacological significance of RNA secondary structure in drug design?

  • It is irrelevant for binding small molecules
  • Secondary and tertiary structures create defined pockets that can be targeted by small molecules or antisense agents
  • Only proteins are drug targets
  • It solely prevents drug uptake into cells

Correct Answer: Secondary and tertiary structures create defined pockets that can be targeted by small molecules or antisense agents

Q36. What is SHAPE chemistry used for in RNA studies?

  • Sequencing DNA only
  • Probing RNA flexibility and secondary structure using selective 2′-hydroxyl acylation
  • Measuring protein concentrations
  • Labeling lipids in membranes

Correct Answer: Probing RNA flexibility and secondary structure using selective 2′-hydroxyl acylation

Q37. Which of the following stabilizes A–U base pairs less than G–C pairs?

  • Hydrophobic interactions
  • Two hydrogen bonds in A–U versus three in G–C
  • Electrostatic repulsion
  • Phosphodiester crosslinks

Correct Answer: Two hydrogen bonds in A–U versus three in G–C

Q38. During in vitro transcription of RNA, which enzyme is commonly used?

  • DNA ligase
  • T7 RNA polymerase (or other bacteriophage RNA polymerases)
  • Reverse transcriptase
  • Restriction endonuclease

Correct Answer: T7 RNA polymerase (or other bacteriophage RNA polymerases)

Q39. What structural feature distinguishes prokaryotic from eukaryotic mRNA?

  • Prokaryotic mRNA always has a 5′ m7G cap
  • Eukaryotic mRNA often has a 5′ cap and a 3′ poly(A) tail, while prokaryotic mRNA usually lacks these features
  • Only prokaryotes have introns
  • Prokaryotic mRNA contains ribozymes exclusively

Correct Answer: Eukaryotic mRNA often has a 5′ cap and a 3′ poly(A) tail, while prokaryotic mRNA usually lacks these features

Q40. Which region of tRNA contains the triplet that pairs with mRNA codons?

  • Acceptor stem
  • Anticodon loop
  • D-loop only
  • TψC loop only

Correct Answer: Anticodon loop

Q41. What is the effect of 2′-O-methylation on RNA?

  • Destabilizes RNA and promotes degradation
  • Increases resistance to nucleases and can modulate structure and function
  • Removes the 5′ cap
  • Causes immediate cleavage by RNase H

Correct Answer: Increases resistance to nucleases and can modulate structure and function

Q42. Which RNAs are components of the ribosome?

  • mRNA and miRNA only
  • rRNA species (e.g., 16S, 23S in prokaryotes) combined with ribosomal proteins
  • tRNA only
  • snRNA exclusively

Correct Answer: rRNA species (e.g., 16S, 23S in prokaryotes) combined with ribosomal proteins

Q43. What is the structural consequence when RNA forms an intramolecular duplex region?

  • Formation of protein secondary structure
  • Creation of double-stranded stem regions that reduce flexibility and can form functional elements
  • Complete linearization of the molecule
  • Removal of modified bases

Correct Answer: Creation of double-stranded stem regions that reduce flexibility and can form functional elements

Q44. How do chemical modifications of RNA bases influence therapeutics such as mRNA vaccines?

  • They always inactivate the mRNA
  • Modified bases like pseudouridine can reduce innate immune recognition and increase translation/stability
  • They prevent encapsulation into lipid nanoparticles
  • They convert mRNA into tRNA

Correct Answer: Modified bases like pseudouridine can reduce innate immune recognition and increase translation/stability

Q45. What is the role of leader and trailer sequences in bacterial mRNA?

  • They are translated into proteins directly
  • Untranslated regions that regulate translation initiation and stability
  • They are polyadenylated in bacteria
  • They code for ribosomal proteins

Correct Answer: Untranslated regions that regulate translation initiation and stability

Q46. Which assay can be used to detect specific RNA sequences in a sample?

  • Western blot
  • Northern blot, RT-PCR or RNA hybridization techniques
  • ELISA for proteins only
  • Chromatin immunoprecipitation

Correct Answer: Northern blot, RT-PCR or RNA hybridization techniques

Q47. Which factor most influences RNA folding pathways in vitro?

  • Ambient light only
  • Ionic conditions (Mg2+, K+), temperature and co-transcriptional folding dynamics
  • Protein translation rates only
  • DNA replication speed

Correct Answer: Ionic conditions (Mg2+, K+), temperature and co-transcriptional folding dynamics

Q48. What characterizes riboswitches in mRNAs?

  • Protein-coding sequences only
  • Structured RNA domains in untranslated regions that bind metabolites and regulate gene expression
  • Permanent covalent modifications that block translation always
  • Only found in eukaryotes

Correct Answer: Structured RNA domains in untranslated regions that bind metabolites and regulate gene expression

Q49. Which property allows RNA to act as both information carrier and catalyst (ribozyme)?

  • Rigid linearity of the backbone
  • Ability of nucleotides to form diverse base-pairing and tertiary interactions enabling specific 3D folds
  • Presence of amino acids in the backbone
  • Its double-stranded DNA-like conformation

Correct Answer: Ability of nucleotides to form diverse base-pairing and tertiary interactions enabling specific 3D folds

Q50. In antisense therapy targeting RNA, which property is critical for effective binding and inhibition?

  • Complete lack of complementarity to the target
  • High sequence complementarity, accessibility of target site and chemical stabilization of the oligo
  • Protease resistance only
  • Ability to form disulfide bonds

Correct Answer: High sequence complementarity, accessibility of target site and chemical stabilization of the oligo

Leave a Comment