What is the primary function of mRNA?

• A. Copies the DNA codons
• B. Synthesized in the nucleus
• C. Attached to tRNA and brings an amino acid
• D. Occurs in cytoplasm

Answer: (A)

The main idea is that mRNA serves as the messenger that carries the genetic code from DNA to the ribosome where proteins are made. During transcription, the DNA sequence is copied into an mRNA molecule, which then provides codons that specify the sequence of amino acids in a protein. The ribosome reads these codons and, with tRNAs bringing the corresponding amino acids, builds the protein in the correct order. That transfer of information from DNA into an RNA blueprint for protein synthesis is why copying the DNA codons describes mRNA’s function so well. The other statements relate to where transcription occurs, or to the role of tRNA or translation, which are not the primary function of mRNA itself.