mRNA moves out of nucleus and attaches to ribosomet. RNA carrying amino-acids bind by their anticodons to the mRNA - by complementary base pairing. Another molecule of tRNA with another amino-acid attaches to the mRNA on the next codon along. The two amino-acids on the tRNA form a peptide bond. The first tRNA now moves away and a new tRNA attaches. This process repeats, adding more amino-acids to the polypeptide-chain. Process ends when a 'stop signal' is reached and completed polypeptide detaches.