Primers (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. Es

Primers (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.