How are the DNA replication products visualized during the Sanger method of DNA sequencing?

• A. By using electron microscopy
• B. By using fluorescently labeled dideoxynucleotides
• C. By using radioactive isotopes
• D. By using magnetic resonance imaging

Answer: (B)

Verified step by step guidance

1. Understand the Sanger method of DNA sequencing, which involves the synthesis of DNA strands using a template strand, where the incorporation of dideoxynucleotides (ddNTPs) terminates the DNA strand elongation.
2. Recognize that each of the four types of ddNTPs (ddATP, ddTTP, ddCTP, ddGTP) is labeled with a different fluorescent dye, allowing for the identification of the terminating base at each position in the sequence.
3. During the sequencing process, the DNA fragments of varying lengths are separated by size using capillary electrophoresis.
4. As the fragments pass through a laser detector, the fluorescent labels are excited, and the emitted light is detected and recorded, allowing for the determination of the DNA sequence.
5. The sequence is read by analyzing the order of the fluorescent signals, which correspond to the order of the bases in the DNA strand.