Which sequence correctly describes steps of protein synthesis?

Which sequence correctly describes steps of protein synthesis?

• A. Translation first, then transcription
• B. DNA replication followed by transcription
• C. Transcription in nucleus produces mRNA; RNA processing; mRNA export; translation at ribosome; initiation, elongation, termination; protein folding
• D. RNA transcription in cytoplasm without processing

Answer: (C)

Protein synthesis moves from transcription to translation, with RNA processing and export in between, and then the new protein folds into its active form. In eukaryotic cells, transcription happens in the nucleus to produce an mRNA blueprint. That mRNA is then edited and processed—adding a 5' cap, a poly-A tail, and removing introns—before it exits the nucleus to the cytoplasm. Once in the cytoplasm, a ribosome binds the mRNA and translation begins, proceeding through initiation, elongation, and termination to build the polypeptide. After synthesis, the polypeptide folds into its functional three-dimensional shape, often with the help of chaperone proteins.

This sequence is the best description because it accurately reflects the order and distinct steps involved in producing a functional protein in a typical eukaryotic cell. The alternative that places translation before transcription would not produce the mRNA template needed for protein synthesis. The option mentioning DNA replication is describing a different process altogether. The one that says transcription occurs in the cytoplasm without processing ignores the nuclear location and essential RNA processing that occurs in eukaryotes.