CAPF AC 2023 Q20: Science & Technology – Biology
For protein synthesis, the amino acids are recognized and carried by:
- (a) mRNA
- (b) snRNA
- (c) miRNA
- (d) tRNA
Answer: (d) tRNA
Explanation
Which RNA carries amino acids
How to think: the letter t in tRNA stands for transfer.
It transfers amino acids to the ribosome.
Each tRNA recognises one amino acid and reads the matching code on the mRNA with its anticodon.
| RNA | Full name | Job |
|---|---|---|
| mRNA | Messenger RNA | Carries the code from DNA to the ribosome |
| tRNA | Transfer RNA | Recognises and carries amino acids; the adapter molecule |
| rRNA | Ribosomal RNA | Forms the ribosome and joins amino acids |
| snRNA | Small nuclear RNA | Splicing of RNA in the nucleus |
| miRNA | Micro RNA | Regulates gene expression |
Shape: tRNA looks like a clover leaf in two dimensions and an inverted L in three.
Answer: (d) tRNA.
Why each option is right or wrong
- (a) Incorrect. mRNA carries the genetic message, not the amino acids.
- (b) Incorrect. snRNA helps in splicing inside the nucleus.
- (c) Incorrect. miRNA regulates genes by silencing mRNA.
- (d) CORRECT. tRNA recognises amino acids and carries them to the ribosome.
Key point
Central dogma: DNA → (transcription) → mRNA → (translation) → protein. tRNA: adapter with anticodon loop and amino acid acceptor end. Codon: three bases; 64 codons; AUG is the start codon.
Remember
tRNA = transfer RNA = carries amino acids.
Common mistakes
- Mixing up mRNA (message) with tRNA (carrier).
- Confusing transcription with translation.
- Thinking ribosomes fetch the amino acids themselves.
Exam tip
Educated guess: the question says carried, and the name transfer RNA means exactly that.
Sources
- NCERT Class XII Biology — Molecular Basis of Inheritance (tRNA, the adapter molecule; translation)
- NCERT Class XI Biology — Biomolecules