RNA Processing, RNA Biology, and Post-Transcriptional Control
RNA as a Regulatory and Structural Molecule
Beyond messenger RNA
RNA molecules are processed, edited, localized, translated, degraded, and deployed as structural and catalytic entities. Post-transcriptional control expands coding potential and allows fine-grained temporal regulation.
Processing events
RNA classes
mRNA
- Protein-coding
- Template for translation
rRNA
- Structural and catalytic core of ribosome
- Highly abundant
Alternative splicing
A single gene can produce multiple protein isoforms through regulated exon inclusion, which is a major source of proteomic diversity in metazoans.
Which feature is most closely associated with nonsense-mediated decay?
Nonsense-mediated decay eliminates transcripts likely to encode truncated or deleterious proteins.
Correct answer: Detection of a premature termination codon in an aberrantly processed transcript
What is the biological advantage of alternative splicing?
Alternative exon usage allows tissue- and stage-specific isoforms.
Correct answer: It increases proteomic diversity and regulatory flexibility from a limited number of genes
Tools for RNA analysis
| Tool | Use |
|---|---|
| RT-qPCR | Transcript quantification |
| RNA-seq | Transcript discovery and abundance |
| CLIP-seq | RNA-binding protein interaction mapping |
| ribosome profiling | Translation footprinting |
| Northern blot | Transcript size and abundance |
Which event occurs earliest during eukaryotic mRNA maturation?
The 5' cap is added very early during transcription and is essential for downstream processing.
Correct answer: 5' capping
Name one major function of microRNAs.
MicroRNAs fine-tune protein output from target mRNAs.
Correct answer: They repress gene expression post-transcriptionally by promoting mRNA degradation or translational repression