Difficulty: Easy
Correct Answer: About 80 nucleotides (≈ 80 bp)
Explanation:
Introduction:tRNAs are among the smallest functional RNAs in cells, optimized for delivery of amino acids to ribosomes. Knowing their approximate size helps interpret gels, blots, and sequencing results in molecular biology.
Given Data / Assumptions:
Concept / Approach:Choose the option that best reflects the accepted average length. Values much larger (100–140) are typical of small mRNAs or snRNAs, not tRNAs; values far smaller (40) are too short to form the cloverleaf and L-shaped structures required for function.
Step-by-Step Solution:
1) Recall typical range: ~73–93 nt.2) Identify the nearest average: ~80 nt.3) Select the option that states ≈ 80 nucleotides.Verification / Alternative check:tRNA gene annotations and tRNA-seq datasets routinely report lengths near 75–90 nt with post-transcriptional CCA addition at the 3′ end, consistent with an ~80-nt average.
Why Other Options Are Wrong:
b–d) Overestimate typical tRNA length; these sizes do not fit standard tRNA architecture.e) Too short to encode the necessary structural elements.Common Pitfalls:Confusing tRNA with snRNA or miRNA size classes; ignoring that “bp” here tracks nucleotide count for single-stranded RNA length.
Final Answer:≈ 80 nucleotides.
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