This process is aided by transfer RNA (tRNA) molecules, which forage for amino acids that float around in the cell (outside of the cell's nucleus and ribosomes). The transfer RNA (tRNA) molecules attach to, and escort individual amino acids to the ribosome, as and when the messenger RNA (mRNA) directs. Each of the 20 different amino acids has at least one of its own purpose-built tRNA molecules, which possess a three-letter code of nucleotides at the stem of the cloverleaf-shaped rRNA molecule.

The ribosome has room for only two tRNA molecules at a time. The messenger RNA (mRNA) molecule (which itself is passing through the ribosome) calls over the first tRNA molecule, which brings with it the specified amino acid. Short sections of the messenger RNA (mRNA) and transfer RNA (tRNA) molecules lock together inside the ribosome (because where these two molecules meet, their three nucleotides are complementary), the whole (locked together) apparatus shifts along by three notches (i.e., nucleotides), and a second tRNA molecule (bearing another amino acid) slips in next to the first tRNA molecule.

Next, the first amino acid (brought in by the first tRNA molecule) jumps over to the second tRNA molecule; joining to the amino acid that was brought in by the second tRNA molecule, thus making the start of a protein (i.e., a poly-amino acid molecule, also known as polypeptide or protein molecule). The empty (first) tRNA molecule falls out of the ribosome, and the whole (locked together) apparatus (i.e., mRNA plus second tRNA molecule) moves three more notches (i.e., nucleotides) along the mRNA molecule to make room for a third tRNA molecule bearing another amino acid, and so on.

This process of creating ever-longer chains of amino acids continues to repeat itself inside the ribosome until the protein (coded for by the DNA, which code was transferred to mRNA, which transferred it to the ribosome) is completed.
TRANSCRIPTION,  COMPLEMENTARY DNA (c-DNA),  CENTRAL DOGMA,  DEOXYRIBONUCLEIC ACID (DNA),  RIBONUCLEIC ACID (RNA),  NUCLEIC ACIDS,  CODING SEQUENCE,  GENETIC CODE,  CELL,  INFORMATIONAL MOLECULES,  CODON,  RIBOSOMES,  POLYRIBOSOME (POLYSOME),  rRNA (RIBOSOMAL RNA),  NUCLEOTIDE,  POLYMER,  TRANSFER RNA (tRNA),  PROTEIN,  AMINO ACID,  POLYPEPTIDE (PROTEIN),  ANTISENSE (DNA SEQUENCE)