1.reverse transcriptase is added to a test tube containing mRNA isolated from a sample of cells.2.reverse transcriptase makes th e first DNA strand and using the mRNA as a template and a short poly-dT as a DNA primer.3.mRNA is degraded be another enzyme.4.DNA polymerase synthesizes the second DNA strand, using a primer in the reaction mixure.(several options exist for primer)5.the result is cDNA which carries the complete coding sequence of the gene but no introns.