Primer: (1) A short (usually 15-30 nt long, depending on application) piece of ssDNAplugin-autotooltip__default plugin-autotooltip_bigSingle-stranded DNA (ssDNA): a polymerized chain of deoxyribonucleotides that is not paired with a complementary polymer. Usually formed by denaturing dsDNA with heat or other methods. that is synthesized in vitroplugin-autotooltip__default plugin-autotooltip_bigIn vitro: taking place outside of a living organism, usually in a test tube or Petri dish. and used in applications such as DNAplugin-autotooltip__default plugin-autotooltip_bigDNA: deoxyribonucleic acid. The genetic material for nearly all life on Earth. sequencingplugin-autotooltip__default plugin-autotooltip_bigSequencing: the procedure used to determine the sequence of a biological polymer such as DNA, RNA, or protein. Although there are indeed biochemical techniques that can be used to directly sequence RNA or protein, these methods are almost never used in modern molecular genetics research - instead, RNA and PCRplugin-autotooltip__default plugin-autotooltip_bigPolymerase chain reaction (PCR): An experimental technique invented by Kary Mullis used to exponentially amplify DNA in vitro. PCR made obtaining large quantities of DNA for analysis much faster and easier than using traditional cloning methods.. In this context, primers can also be called oligonucleotides. (2) a free 3'-OH end on a nucleic acid that can be used for initiating DNAplugin-autotooltip__default plugin-autotooltip_bigDNA: deoxyribonucleic acid. The genetic material for nearly all life on Earth. synthesis.