RT-PCR

"Reverse transcription polymerase chain reaction" is a five-word mouthful for something more easily said in four simple words: "turning RNA into DNA." The polymerase chain reaction (PCR) single-tubedly revolutionized molecular biology and changed the pace of research in the field forever. It was such an important development that like many other important scientific techniques (including electron microscopy and centrifugation (here called "disperse systems)), it won the Nobel Prize in 1993 and rightfully so. In short, what PCR does is turn a very small amount of DNA into a lot of DNA, still microscopic of course but enough that scientists can actually work with and manipulate it. Here's a video of the process.

The "reverse transcription" means a lot of what it implies. Just as I said how transcription was turning DNA into RNA, the reverse of that process turns RNA into DNA. Viruses are unique in terms of "living" things (viruses are technically not considered living because they need a host in which to reproduce) because some of them use RNA (single stranded or double stranded) as their genetic blueprint instead of DNA (like we and every other organism in every kingdom of life do). HIV is one such example of an RNA-virus. As suggested, these viruses have the natural ability to turn RNA into DNA, a process they need to do in order to integrate their genetic material into that of their hosts'. To do our research, we borrow the special enzyme they use called "reverse transcriptase." It's actually quite remarkable how many uses scientists have for viruses and their products.

So for RT-PCR, instead of the normal DNA polymerase (an enzyme that joins DNA nucleotides together), we use reverse transcriptase. And since we want to convert all of our RNA into DNA (all of the genes), we use random primers (short sequences of nucleotides that specific a part of the genome to amplify) instead of specific ones (those come into play later when we hone into one gene).

Unlike the laborious process of RNA isolation, RT-PCR is quite simple and is just me making up a mix, aliquoting it into tubes with my RNA, then throwing all those tubes into a machine that does the heating and cooling (cycling) for me according to a program a lab mate set up. All I have to do is come back in a couple hours and boom, collect my DNA. Kinda like magic. Then again, a lot of science seems like magic....

Next up: Real-time PCR!