In transcription ,the template strand is what is used as a template in the synthesis of mRNA. In translation, a mature mRNA strand is translated in the 5'→3' direction by a ribosome to produce a polypeptide chain. Reading frames in the 3'→5' direction on the mRNA strand may be disregarded during translation.
The linkage of an amino acid to a tRNA is crucial for two reasons. First, the attachment of a given amino acid to a particular tRNA establishes the genetic code. When an amino acid has been linked to a tRNA, it will be incorporated into a growing polypeptide chain at a position dictated by the anticodon of the tRNA. Second, the formation of a peptide bond between free amino acids is not thermodynamically favorable. The amino acid must first be activated for protein synthesis to proceed.
A ribosome is a complex macromolecule composed of structural and catalytic rRNAs, and many distinct polypeptides. In eukaryotes, the synthesis and assembly of rRNAs occurs in the nucleolus.