Matthew G. answered • 05/27/22
General Biology, Chemistry, and Math Tutor
I know this question is referring to how is DNA replicated within your own cells, but I'd like to take this question a different direction. There is another way that DNA can be replicated through technology! This is how scientists or doctors can identify if you had COVID (a virus) or if you have strep throat (caused by a type of Streptococcus bacteria). It is called Polymerase Chain Reaction or commonly called PCR. The coolest thing about PCR is that you can target specific pieces of DNA. For example, if you wanted to identify if you have COVID you would specifically target for a gene that codes for a unique protein that only that virus has. In the same way that you have genes that code for the color of your eye, there is a code for every single different protein. To continue with PCR, there are 5 main steps to replicating DNA without a cell.
- A mixture of a sample of DNA, a bunch of nucleotides, primers (a specific primer that you make in a lab to go right in front of your target gene), and polymerases (which come from a bacteria called Thermus aquaticus that can withstand high temperatures) is put into a machine called a Thermo Cycler.
- The mixture is heated up so that the DNA strands come apart without an enzyme(which would usually be done by helicase)
- The mixture is slightly cooled so that the primers will bind to the DNA
- The mixture is heated slightly to a temperature that the polymerases like to work and then they will extend the DNA sequence.
- This cycle is repeated about 30 times
What is amazing about this is that each cycle that you do, the amount of DNA doubles. By the end, you can have billions of copies! In the case of COVID, if you happened to have covid, you would have many copies of the gene. If you didn't have COVID, nothing would happen at step 3 because the primer would not bind to the DNA.
(PCR can actually be a lot more complicated than this, but these are the principles that make it work)
