Name a common diagnostic application of PCR.

Name a common diagnostic application of PCR.

• A. Cloning of genes into plasmids
• B. Detection of pathogen DNA
• C. Gel electrophoresis of DNA fragments
• D. RNA transcription analysis

Answer: (B)

PCR used diagnostically hinges on amplifying a pathogen-specific DNA sequence to detectable levels. By designing primers that bind only to a region unique to the pathogen, the reaction multiplies that DNA if it’s present in the sample. The result is a fast, highly sensitive test that can detect even tiny amounts of pathogen DNA and help confirm infections or monitor outbreaks. Other uses described are more about non-diagnostic lab tasks. Cloning genes into plasmids is a research technique for studying gene function or propagating sequences, not a routine diagnostic test. Gel electrophoresis is a method to separate and visualize DNA fragments and can verify PCR results, but the actual diagnostic readout comes from detecting the presence of the pathogen’s DNA. RNA transcription analysis focuses on gene expression, often involving measuring RNA levels (sometimes with RT-PCR), which targets RNA activity rather than directly identifying a pathogen’s DNA in a clinical sample.

PCR used diagnostically hinges on amplifying a pathogen-specific DNA sequence to detectable levels. By designing primers that bind only to a region unique to the pathogen, the reaction multiplies that DNA if it’s present in the sample. The result is a fast, highly sensitive test that can detect even tiny amounts of pathogen DNA and help confirm infections or monitor outbreaks.

Other uses described are more about non-diagnostic lab tasks. Cloning genes into plasmids is a research technique for studying gene function or propagating sequences, not a routine diagnostic test. Gel electrophoresis is a method to separate and visualize DNA fragments and can verify PCR results, but the actual diagnostic readout comes from detecting the presence of the pathogen’s DNA. RNA transcription analysis focuses on gene expression, often involving measuring RNA levels (sometimes with RT-PCR), which targets RNA activity rather than directly identifying a pathogen’s DNA in a clinical sample.