Before revision: Ribosome is a molecular machine that polymerizes a protein where the sequence of the amino acid subunits of the protein  is dictated by the sequence of codons (triplets of nucleotide subunits ) on a messenger RNA (mRNA) that serves as the template.
After revision: Ribosome is a molecular machine that polymerizes a protein where the sequence of the amino acid subunits of the protein , is dictated by the sequence of codons (triplets of nucleotide subunits ) on a messenger RNA (mRNA) that serves as the template.