Question

The size of mRNA is generally related to

• A. the number of codons it has
• B. the size of the ribosome
• C. the size of entire DNA molecule
• D. the number of anticodons it has

Hint:

Rule: 1 codon = 3 nucleotides $\rightarrow$ mRNA length depends on number of codons

Answer 1

The Correct Option is A

Concept: mRNA (messenger RNA) carries genetic information from DNA to ribosomes in the form of codons, which are sequences of three nucleotides.
• Each codon codes for one amino acid.
• The length (size) of mRNA depends on how many codons it contains.
• More codons $\Rightarrow$ longer mRNA $\Rightarrow$ larger protein.

Step 1: Understand mRNA structure.
mRNA is a linear sequence of nucleotides arranged as codons (triplets).

Step 2: Relate size to function.
The number of codons determines how many amino acids will be synthesized, and hence directly determines mRNA length.

Step 3: Analyze options.
• (A) Number of codons: Correct
• (B) Ribosome size: Independent of mRNA length
• (C) Entire DNA size: Not directly related
• (D) Anticodons: Present on tRNA, not mRNA

Step 4: Conclusion.
Thus, mRNA size is related to the number of codons. Final Answer: Option (A)