Question

DNA sequencing using the Sanger method requires?

1) Polymerase chain reaction (PCR)
2) Gel electrophoresis
3) DNA polymerase
4) DNA ligase

Answer 1

Sanger method of DNA sequencing requires DNA polymerase for the synthesis of DNA strands and gel electrophoresis to separate DNA fragments; PCR and DNA ligase are not directly involved in the sequencing process.

Step-by-step explanation:

DNA sequencing using the Sanger method requires several components and steps, and among the options given, the correct answers are gel electrophoresis and DNA polymerase. DNA polymerase is essential for the synthesis of the new DNA strands, while gel electrophoresis is used to separate the DNA fragments based on size and to allow for the determination of the sequence with a laser scanner.

Although Polymerase Chain Reaction (PCR) is used to amplify DNA, it is not necessarily part of the Sanger sequencing method itself. DNA ligase is involved in the process of molecular cloning and DNA repair but is not required for Sanger sequencing. Sanger sequencing begins with denaturation of the DNA sample, followed by the addition of a primer, DNA polymerase, and a mixture of normal nucleotides and labeled dideoxynucleotides, which terminate the DNA chain elongation. As each terminated fragment represents the end point of synthesis when incorporating a labeled nucleotide, gel electrophoresis is used to separate these fragments to determine the DNA sequence.