Explain the role of messenger RNA (mRNA) in protein synthesis.

Edexcel A-Level Biology A: Salters-Nuffield (9BN0) — 1.4 DNA, RNA and protein synthesis · Explain · 5 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Protein synthesis involves two main stages: transcription and translation. During these stages, genetic information is converted into a functional protein.

Model answer (5 marks)

mRNA is produced in the nucleus during transcription.
mRNA carries the genetic information from DNA to the ribosome.
mRNA moves out of the nucleus into the cytoplasm and binds to a ribosome.
mRNA contains a sequence of codons that specifies the order of amino acids.
mRNA directs the joining of amino acids in that order to form a protein during translation.

Examiner tips

  • Use the exact phrase "mRNA is produced in the nucleus" to secure the first point. Show the flow: DNA → mRNA → ribosome → protein. Mention codons and amino acid sequence to hit the last two points. Keep each point brief and separate with a line break.

Common mistakes

  • Confusing mRNA with tRNA or rRNA. Failing to state that mRNA moves out of the nucleus. Omitting the role of codons in specifying amino acid order.

Mark scheme (5 marks)

  1. mRNA is made in the nucleus / mRNA is produced during transcription
  2. mRNA carries/contains the genetic code/information from DNA (to the ribosome)
  3. mRNA moves out of the nucleus to the ribosome / mRNA travels to the ribosome in the cytoplasm
  4. the sequence of bases (codons) on mRNA codes for a specific sequence of amino acids
  5. amino acids are joined together in the order determined by mRNA to form a protein / translation occurs at the ribosome

Key terms in this question

messenger RNA (mRNA)

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