Each RNA has its own job
- The idea
- Predict
- See it
- Why
- Check
The idea
“Any of the three RNAs can build the ribosome, carry amino acids or get a cap and tail.”
All three are RNA, and diagrams pile them into one ribosome. Their jobs blur together easily.
The short version
The mistake: Any of the three RNAs can build the ribosome, carry amino acids or get a cap and tail.
What's actually true: mRNA carries the codons, tRNA brings the matching amino acid, and rRNA builds the ribosome and joins the amino acids.
- A ribosome reads mRNA codon by codon, then lets it go.
- tRNA is the adaptor, with an anticodon at one end and the matching amino acid at the other.
- rRNA joins the amino acids, making the ribosome a ribozyme, an RNA catalyst.
- snRNA works in spliceosomes in the nucleus, cutting introns out of pre-mRNA. It isn't part of translation.
On the exam: mRNA is read, tRNA delivers amino acids, and rRNA builds the ribosome and joins them.