Applications of single-stranded DNA vectors Single-stranded vectors are particularly useful for which purposes in molecular biology?

Introduction / Context:
Vectors that can generate single-stranded DNA (ssDNA), such as M13 derivatives and phagemids with f1 origins, have specialized uses in sequencing, mutagenesis, and probe generation. Understanding why ssDNA is advantageous clarifies vector selection.

Given Data / Assumptions:

• Sequencing methods historically (e.g., Sanger) favored ssDNA templates.
• Site-directed mutagenesis workflows often require ssDNA intermediates.
• Probe labeling can be simpler with ssDNA templates.

Concept / Approach:
ssDNA avoids issues like re-annealing of complementary strands, simplifies primer access, and enables efficient incorporation of modified nucleotides. Phagemids combine plasmid features with filamentous phage origins to produce ssDNA when helper phage is present.

Step-by-Step Solution:

Verification / Alternative check:
Protocols from classic M13 systems and modern phagemids (e.g., pBluescript with f1 ori) support these applications.

Why Other Options Are Wrong:

• Any single item alone is incomplete; all listed uses apply.
• “None of the above” contradicts established practice.

Common Pitfalls:
Confusing ssDNA production (requires helper phage) with routine plasmid prep (dsDNA).

Final Answer:
All of the above