Exons are defined as the nucleotides that are necessary to make the protein.

Exons are defined as the nucleotides that are necessary to make the protein.

• A. Exons
• B. Introns
• C. Promoters
• D. Terminators

Answer: (A)

Understanding how genes are organized and processed helps explain why exons are the nucleotides used to make the protein. In eukaryotes, a gene is transcribed into a precursor messenger RNA that contains both exons and introns. The introns are removed during RNA splicing, and the remaining exons are joined to form the mature mRNA. This mature transcript is what gets translated into a protein, so the nucleotide sequences that stay in the final message are the ones that ultimately determine the amino acid sequence. Promoters and terminators, on the other hand, are regulatory DNA elements that control where transcription starts and ends and are not part of the mature mRNA. Keep in mind that while exons mainly carry the coding information, some exons also contain untranslated regions that are transcribed but not translated; the core idea remains that exons are the portions retained to make the protein.

Understanding how genes are organized and processed helps explain why exons are the nucleotides used to make the protein. In eukaryotes, a gene is transcribed into a precursor messenger RNA that contains both exons and introns. The introns are removed during RNA splicing, and the remaining exons are joined to form the mature mRNA. This mature transcript is what gets translated into a protein, so the nucleotide sequences that stay in the final message are the ones that ultimately determine the amino acid sequence. Promoters and terminators, on the other hand, are regulatory DNA elements that control where transcription starts and ends and are not part of the mature mRNA. Keep in mind that while exons mainly carry the coding information, some exons also contain untranslated regions that are transcribed but not translated; the core idea remains that exons are the portions retained to make the protein.