Learning outcomes: describe and give examples of each tool of recombinant dna, outline general strategies for cloning and expressing a prokaryotic or eukaryotic gene in, coli, and for creating transgenic organisms. Synthetic oligonucleotides: oligonucleotide: synthetic, laboratory made short dna or rna molecules (oligomers) used in research, genetic testing, and forensics. In the lab, accurate, automated synthesis of up to about 200 base pairs is routine: longer sequences can be obtained by joining strands together, single stranded oligonucleotides are useful as hybridization probes and as primers for. Intrinsic factors: a:t / g:c ratio: the higher gc content, the higher the tm. For fragments of up to about 13 base pairs: Polymerase chain reaction (pcr): pcr: a technique used to amplify (produce large amounts of) a specific dna fragment. It is possible to amplify a fragment even if only one copy of the fragment is present in the dna source.