The main difference is in the way you read the output. In a typical lab, you'd use PCR and qPCR for slightly different purposes.
In PCR, you take the DNA you've amplified and read it yourself, usually in a process called gel electrophoresis. This allows you to visualize the amplified DNA by fluorescence directly with your own eyes. It's easy to characterize the PCR product, for example to answer:
- is a given target DNA present/absent in my sample?
- are there multiple versions of a given gene in my sample?
- what's the size of the amplified DNA?
Traditional PCR also tends to be the preferred method when preparing DNA for other biotech experiments (e.g. a ligation, cloning, or sequencing).
In qPCR, fluorescence is detected directly inside the PCR machine by an optical reader. This allows very precise quantification of how much DNA is being made at each PCR cycle. This can be helpful:
- to quantify how strongly a gene is expressed in different tissues
- to minimize user involvement
PCR and qPCR are based on the same thermal process and chemistry that was awarded the Nobel Prize in 1993.
Lastly, qPCR machines and reagents are more expensive than traditional PCR.
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