Automated DNA sequencing based on Sanger chain termination typically uses which primer/dye strategy?

Introduction / Context:
Sanger sequencing (chain termination) underpins most automated capillary sequencing systems. The method requires a defined primer to initiate DNA synthesis and fluorescent labeling for automated base calling.

Given Data / Assumptions:

• Sequencing is based on chain termination chemistry.
• Automation implies fluorescence detection.
• We compare primer and labeling strategies.

Concept / Approach:
Two fluorescence strategies exist: dye-primer (fluorescent label on the primer) and dye-terminator (fluorescent ddNTPs). Both require an oligonucleotide primer. A polynucleotide primer is not used, and sequencing cannot proceed without a primer.

Step-by-Step Solution:
1) Chain termination needs a 3'-hydroxyl provided by a primer annealed to template.2) Automation relies on fluorescent signals to identify terminated fragments.3) In dye-primer chemistry, the primer itself carries the fluorophore; in dye-terminator, ddNTPs are labeled, but an unlabeled oligonucleotide primer is still used.4) Therefore, the only correct statement among the options is that an oligonucleotide primer labeled with a fluorescent dye is used (captures dye-primer usage and affirms primer necessity).

Verification / Alternative check:
Even when dye-terminator chemistry is chosen, an oligonucleotide primer is required. Options claiming “no primer” are incompatible with DNA polymerase mechanics.

Why Other Options Are Wrong:
Polynucleotide primer: not the standard practice for Sanger sequencing.No primer: impossible for polymerase initiation on single-stranded template.Either polynucleotide or no primer: both contradict core requirements.

Common Pitfalls:
Confusing dye-primer vs dye-terminator and concluding that a primer is unnecessary; using the term “polynucleotide primer,” which is non-standard in this context.

Final Answer:
An oligonucleotide primer labeled with a fluorescent dye