Translation occurs on ribosomes, where tRNAs act as connectors between the mRNA template and the amino acids that are assembled into the protein. In eukaryotic cells, mature mRNA molecules must exit the nucleus and move to the cytoplasm, where ribosomes are found for translation. In contrast, in prokaryotic cells, ribosomes can bind to the mRNA while it is still being transcribed. This means translation can start at the 5' end of the mRNA even though the 3' end is still connected to the DNA.