"Proteins are produced in tiny factories inside the cells... Biologists call them ribosomes. ...A DNA sequence that corresponds to the relevant protein sequence is copied onto another molecule... called a 'messenger', which transmits a form of the sequence to the ribosomes. The messenger molecules, called ... are another kind of sequence. The DNA sequences are... a kind of template... sequence of s... transcribed to produce the message... translated into an amino-acid sequence when the protein is made. (s are the units of which protein is made, just as nucleotides are the units of which DNA is composed)."