Which part of a gene forms the coding sequence that can be translated into protein?

• A. Exons.
• B. Introns.
• C. Regulatory areas.
• D. Introns and exons equally noncoding.

Answer: (B)

The coding sequence that becomes a protein comes from exons. In gene transcription, the entire gene is transcribed into a pre-mRNA that includes both exons (the coding parts) and introns (noncoding interruptions). The introns are removed and the exons are joined together to form mature mRNA, which is then translated into protein. Regulatory areas are not translated, and introns, even though transcribed, do not contribute to the final protein sequence. So exons are the parts that form the protein-coding sequence.