what does PCR stand for? (in biology)?

Question

what does PCR stand for? what does this technique allow you to do to genes?

Answer 1

Polymerase chain reaction

It's a technique for amplifying a SPECIFIC gene out of an entire sample of DNA. So, instead of getting multiple copies of an entire chromosome, you get just the area you want.

It works by having two primers, one for each end of the gene you want (the 5' ends on opposing strands). The machine does a series of reactions in which these strands undergo replication, so that eventually the % of your desired regions far outnumbers the original complete DNA set.

Why do this? It's often used to determine gene expression. Do something to an organism - you're looking for how it responds. You actually use cDNA, or DNA made by reverse transcribing mRNA. mRNA indicates that the organism is producing a certain protein in response to whatever perturbation the researcher imposes on it. Anyway, using PCR in this way allows researchers to see how an organism is reacting via looking indirectly at what proteins it's making.

Answer 2

Think of it like DNA xeroxing: you make lots of copies of a particular piece of DNA. You need to have two primer pieces of DNA for the reaction to start from - one at each end of the piece you want to copy; you need the DNA polymerase (a polymerase is an enzyme that builds nucleotide polymers from single nucleotides); you need the nucleotide pieces to build the copies with; and you need a special salt buffer that is similar to the solution inside the cell where DNA replication would normally take place. Put all this stuff together and heat it up to separate the DNA strands, cool it down to the temperature the enzyme works at, let it make a copy, then heat it up again to separate the pieces again so they can all be used to make copies of, and repeat the cycle. Do this over and over, and you end up with huge amounts of DNA of the same sequence from whatever DNA template you started with. This product DNA can then be run out on an agarose gel to see how big it is, it can be directly sequenced, it can be put into a plasmid (a circular piece of DNA) and popped into a bacterium to be copied even more, it can even be modified using PCR to create a mutant gene that can be inserted into an oocyte to see how that mutation affects a living animal. There's lots of things you can do with PCR. The big problem is that it's very easy to get alternative DNA sources into your reaction, and these contaminating DNAs can act as templates to produce 'wrong' product. There are other problems, too, but that's the biggest.

Answer 3

polymerase chain reaction

and that's a trick question you don't just use it on genes you can use it on any DNA including promoter and "junk" regions, you can even use it on RNA

it allows you to do an amost infinate number of things to genes, and even more stuff to things that aren't genes. You can clone genes, sequence genes (by a modified version of PCR), detect whether genes are present in the organism (by amplifying a chunk then running on a gell), detect how much they ar expressed (using RT-PCR on the RNA transcript).

the short answer is it allows you to artifilly replicate, tanslate and/or reverse translate short segments of DNA or RNA (which i guess could be genes or gene transcripts).

your primer design helps you select specific sequences to amplify.

Answer 4

Polymerase Chain Reaction. I allows dna to begin the replication process....create a new strand of dna from an existing one.

Answer 5

Any of various large, tailless Old World primates of the family Pongidae, including the chimpanzee, gorilla, gibbon, and orangutan.