Eukaryotic pre-mRNA processing
- When an RNA transcript is first made in a eukaryotic cell, it is considered a pre-mRNA and must be processed into a messenger RNA (mRNA).
- A 5' cap is added to the beginning of the RNA transcript, and a 3' poly-A tail is added to the end.
- In splicing, some sections of the RNA transcript (introns) are removed, and the remaining sections (exons) are stuck back together.
- Some genes can be alternatively spliced, leading to the production of different mature mRNA molecules from the same initial transcript.
- Addition of cap and tail molecules to the two ends of the transcript. These play a protective role, like a book's front and back covers.
- Removal of "junk" sequences called introns. Introns are sort of like blank or messed-up pages made during a book's printing, which have to be removed in order for the book to be readable .
Overview of pre-mRNA processing in eukaryotes
- Addition of a 5' cap to the beginning of the RNA
- Addition of a poly-A tail (tail of A nucleotides) to the end of the RNA
- Chopping out of introns, or "junk" sequences, and pasting together of the remaining, good sequences (exons)
5' cap and poly-A tail
Try it yourself: Splice the message
- If you remove the purple sequences, you should get this series of letters:
- If you group the remaining letters into sets of three, you should get this message: