Polymerase chain reaction (PCR).
PCR has had some very recent real-world applications. At the start of the Coronavirus spread in the US, the CDC was tasked with designing and manufacturing a PCR-based test for the virus. While tests already existed in Europe and Asia, the CDC made a slightly more complicated test that allowed them to test two regions of the virus genome and one region that should be common among all Coronaviruses, not just the most recent version. This last piece would allow the research community to study the relationship between previous coronavirus infections and the most recent virus.
The test was beset with problems. In order to understand what went wrong, scientists had to do a number of critical controls. The gel below is an example of what can happen in PCR. See the gel at the link below and identify several things that could have gone wrong. You should 1) identify the error and 2) explain how that might have happened.
Gel of PCR results: PowerPoint slide that I attached in the additional material