Regulating Translation
Biology: AQA A Level, topic 8.2.8
RNA Interference (RNAi)
Gene expression can be prevented in eukaryotes and some prokaryotes by preventing translation of mRNA. Translation can be inhibited by molecules called RNA interference (RNAi).
Translation
- Translation is a process involved in synthesising proteins using the genetic code.
- After transcription, mRNA moves from the nucleus to the cytoplasm.
- Translation reads the sequence of bases on mRNA and joins the corresponding amino acids together to produce a protein.
RNAi
- RNAi is a small molecule of double-stranded RNA.
- RNAi interferes with mRNA by binding to the mRNA molecule and breaking it down.
- Interfering with mRNA prevents it from being translated into protein.
- RNAi influences gene expression in this way.
siRNA
- siRNA is a type of RNAi that is complementary to the mRNA sequence it inhibits.
- siRNA targets a specific sequence of mRNA.
- After siRNA has bound to mRNA, the mRNA is broken down into smaller fragments.
- The fragments of mRNA are degraded.
miRNA
- miRNA is not fully complementary to the mRNA sequence.
- miRNA can target multiple sequences of mRNA.
- After miRNA has bound to mRNA, the mRNA is either degraded or stored for future use.
Test yourself on Regulating Translation
What feature differentiates siRNA from miRNA?