RNA Splicing Removes Introns in Eukaryotes

Steps:

• Identify non-coding RNA sequences: These are introns, which do not code for proteins.
• Recall transcription process: In eukaryotes, pre-mRNA contains both exons (coding) and introns (non-coding).
• Understand removal step: After transcription, introns are spliced out to form mature mRNA.
• Match to cell type: This splicing occurs only in eukaryotic cells, not prokaryotes.

Why B is correct:

• Introns are non-coding sequences removed via splicing in eukaryotic cells, as defined in molecular biology for mRNA processing.

Why the others are wrong:

• A: Exons are coding sequences retained, not removed, in eukaryotes.
• C: Exons are coding and not removed; prokaryotes lack introns entirely.
• D: Introns exist but are not removed in prokaryotes, which have simpler transcription without splicing.

Final answer: B