MCAT® ExamBiological and Biochemical Foundations of Living SystemsEasy
A genetics researcher is studying a novel eukaryotic gene that produces a protein with a molecular weight of 50 kDa. They discover that the initial RNA transcript is significantly longer than the mRNA found in the cytoplasm and contains multiple non-coding regions. Which of the following processes is responsible for removing these non-coding regions and producing the mature mRNA?
- ATranslation
- BPolyadenylation
- CTranscription
- DRNA splicing
Show answer & explanationAnswer & explanation
Correct answer: D. RNA splicing
In eukaryotes, initial RNA transcripts (pre-mRNA) contain both coding regions (exons) and non-coding regions (introns). RNA splicing is the process by which introns are removed and exons are ligated together to form the mature mRNA.
Why the other options are wrong
- A. Translation is the synthesis of protein from an mRNA template.
- B. Polyadenylation is the addition of a poly-A tail to the 3' end of mRNA, important for stability and translation, but doesn't remove introns.
- C. Transcription is the synthesis of RNA from a DNA template.
Eukaryotic mRNA Processing
A series of modifications that convert a primary RNA transcript (pre-mRNA) into a mature mRNA molecule in eukaryotes.
- Occurs in the nucleus.
- Involves 5' capping, 3' polyadenylation, and splicing.
- Removes introns and joins exons.
- Essential for stable, translatable mRNA.
Memory trick: Splice the Introns, Save the Exons