Summary
In eukaryotes, pre-mRNA gets a 5 prime cap, a poly-A tail and has introns spliced out.
In depth
The 5' cap protects the mRNA and aids ribosome binding; the poly-A tail (about 200 adenines) stabilises it and helps export. Splicing removes introns. These steps occur co-transcriptionally.
Only properly processed mRNA is exported.
Capping happens first, with a guanine nucleotide joined by a 5 prime to 5 prime triphosphate linkage and methylated; the cap is recognised by eIF4E. Cleavage and polyadenylation need a signal AAUAAA in the transcript. Introns are removed by splicing, and the three steps are coupled to transcription through the polymerase tail.
RNA editing alters bases after transcription: ADAR enzymes change adenosine to inosine, and APOBEC changes cytosine to uracil, as in the apoB gene, where editing yields a short protein in the intestine and a long one in the liver.
Frequently asked questions
What is RNA Processing?
In eukaryotes, pre-mRNA gets a 5 prime cap, a poly-A tail and has introns spliced out.
Which area of biology covers RNA Processing, and how advanced is it?
RNA Processing is one of the 52 topics in Molecular Biology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Splicing, Transcription, Primase and RNA Primer.
Why does RNA Processing matter?
Processing only exists in eukaryotes, and errors cause diseases such as spinal muscular atrophy and some beta-thalassaemias.
Can you give an example of RNA Processing?
The mRNA of beta-globin is about 1600 nucleotides but the gene region is longer because of introns.
What should I learn before RNA Processing?
Work through the Beginner topics in Molecular Biology first, such as Central Dogma, DNA Replication, Base Pairing, then return to RNA Processing. Intermediate topics assume the Beginner vocabulary.
What topics are related to RNA Processing?
The closest topics to RNA Processing are Splicing, Transcription, Primase and RNA Primer, Okazaki Fragments. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand RNA Processing?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for RNA Processing. To practise the whole of Molecular Biology, use the Molecular Biology quiz.
How is RNA Processing different from Splicing?
RNA Processing: In eukaryotes, pre-mRNA gets a 5 prime cap, a poly-A tail and has introns spliced out. Splicing: The removal of introns and joining of exons by the spliceosome to produce mature mRNA. Read both side by side and note what each one explains.
How should I study RNA Processing step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Splicing and explain the difference aloud. Finally, take the Molecular Biology quiz and come back to this page for any question you miss.