Eukaryotic mrna have a poly (a) tail at 3" end: create primer with 15 deoxythymidines (dt15, can create a (15 20 nt) oligo (dt) chain that binds to 3" end if you know the mrna sequence, mix oligo(dt15) primers with mrna binds to the mrna, add reverse transcriptase and dntps, synthesize dna strand, add rnase h, dnap and atp to digest rna strands, degrade the mrna by naoh or rnase, dnap copies first strand cdna using rna segments as primer, fragments joined by dna ligase = cdna. *amplify dna cdna acts as a template: use two primers: ~50 pmol used in excess over the template, mix oligonucleotide primers, template, dnap and dntps, dnap makes a duplex with dna (extension, heat to denature duplex => two templates made, cool so the two primers will bind its respective template = annealing, perform denaturation extension cycle for n time.