PCR test amplifies DNA which then allows you to test whether specific DNA pieces are found in the sample. It's a proven technology that's widely used. Just because it was misused as a diagnostic tool during covid doesn't makethe underlying technology flawed or invalid.
It amplifies pieces of RNA, ie not a whole genetic sequence but a snippet. From the snippet that's amplified, they take an average of the particles generated by the polymerization and infer the sequence based on that statistical average. It's like taking a bag of pebbles, weighing the bag and using the weight to determine the physical shape of each individual pebble. It's not that reliable and it's prone to giving false positives, you have to use very limited material, and you have to be very careful about how many times you amplify it. If you amplify too little you can't see the protein because there isn't a statistical pattern you can be confident in, if you amplify too much you risk denaturing the proteins you're trying to amplify.
Plus the technique is rife with confirmation bias.
They use primers to aplify specific parts of a DNA strand, and add flourescent dyes during the PCR process. The more the resulting liquid flouresces the more of that genetic material you had to begin with.
What is the PCR process? Without googling it.
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