Translation

Types of RNA

pre-mRNA
unmodified RNA formed right after transcription.
mRNA
RNA that carries assembly code for polypeptide.
tRNA
translates RNA code to specific amino acid.
rRNA
forms ribosomes that assemble the polypeptide (a RNA enzyme!).

Codons

Eukaryotic Translation Step-by-Step

  1. mRNA and initiator tRNA bind to small ribosomal subunit.
  2. Large ribosomal subunit arrives. We are good to go.
  3. Ribosomal subunits made of rRNA and proteins.
  4. Somewhere in cytosol, a tRNA finds and binds to its unique amino acid.
  5. tRNA (and amino acid) with correct anticodon binds to mRNA codon.
  6. Ribosome scoots mRNA along, peptide bond forms.
  7. Expended tRNA is released.
  8. Repeat steps 5 thru 7 until stop codon reached.
  9. mRNA and ribosomal subunits disassociate. Party's over.
  10. Several ribosomes might be cruising along a mRNA.
  11. Polypeptide will be folding as its being made.
  12. Other functional groups or molecules might be added to polypeptide.