What is an "open system" when it comes to PCR machines?
In an open system, &quot;mRNAs are detected because of their property of being expressed in the tissue sample isolated for study. This approach is in contrast to what are called closed-system approaches, in which the mRNAs to be detected are selected as candidates in advance of analysis; a contemporary example of a closed system would be a gene “chip” hybridization experiment.&quot; [Sutcliffe, J.G. (2001) J. Neurosci. 21:8306-9. “Open-System Approaches to Gene Expression in the CNS”] https://doi.org/10.1523/JNEUROSCI.21-21-08306.2001