Copy the pure mRNA into a DNA molecule (cDNA = complementary DNA) using an enzyme called "reverse transcriptase" and the precursors of DNA called nucleotides.

Insert the cDNAs into a plasmid, a circular replicating DNA element, so that you can make move the gene into a bacterium (this step involves use of restriction enzymes [to cut] and ligase [to paste]. The insert is placed behind a transcriptional promoter to make more RNA.