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False positives for PCR can only plausibly happen through contaminated samples. You should take some time to investigate how PCR works.
by ouid 5y ago
False positives for PCR can only plausibly happen through contaminated samples. You should take some time to investigate how PCR works.
- sterlind 5y agofrom what I've read, each round of PCR has a chance of copy errors in a small fraction of the samples. after too many rounds, random noise is generated and amplified. false positives can occur from this noise if the number of rounds is too high, which is why they cap PCR cycles rather than letting it bake forever.
- robbiep 5y agoI’m not sure why this has been downvoted, this is a correct answer - it is possible to generate false positives by running too many cycles
- G3rn0ti 5y agoPrimers (DNA pieces that „select“ the right DNA sequence to be amplified) can sometimes attach randomly on DNA and hence make PCR copy/amplify the wrong DNA. Especially, if the primer’s got bad (partially degraded for example). If you don’t sequence the resulting end product you only detect that there was DNA amplified and might conclude the sample was positive even if it wasn’t. Copying DNA does not work perfectly like copying files.