Final answer:
In a PCR reaction tube, you would not include components such as enzymatic inhibitors, contaminating DNA or RNA, reagents not specific to the desired sequence, or fluorescently labeled ddNTPs, which are used in sequencing rather than PCR amplification.
Step-by-step explanation:
Components Not Included in PCR Reaction Tubes
For a successful PCR (Polymerase Chain Reaction), certain components are essential, such as a DNA template, primers, DNA polymerase, and dNTPs. However, the components you would NOT include in the reaction tube for PCR are any substances that inhibit the reaction, such as enzymatic inhibitors, contaminating DNA or RNA, and reagents not specific to the sequence you want to amplify. In particular, fluorescently labeled ddNTPs are not a standard component for PCR as they are typically used in sequencing reactions rather than PCR amplification.
It's important to verify that the reaction mix is at the bottom of the tube, which can be achieved by briefly centrifuging the tubes before placing them into the PCR machine. Fluorescently labeled ddNTPs are not standard in PCR because they terminate DNA strand elongation, which is counterproductive for amplification purposes. Ensuring the correct setup and absence of inhibitory substances is crucial for the thermocycler to effectively alter and control the different temperatures required during the cycles of PCR.