Can be used to analyze DNA by transferring to a nylon membrane and probing for fragments?

• A. PCR
• B. Southern blot
• C. Sanger Sequencing
• D. RFLP

Answer: (D)

Transferring DNA fragments to a membrane and probing for them is Southern blotting. In this technique, DNA is first cut with restriction enzymes to create fragments, these fragments are separated by gel electrophoresis, then they are transferred to a nylon (or similar) membrane and exposed to a labeled DNA probe that is complementary to the sequence of interest. After hybridization, the probe binds only to the fragments containing the target sequence, allowing visualization of those specific fragments.

This method is classically used to detect restriction fragment length polymorphisms and to assess gene presence or copy number. PCR, on the other hand, amplifies DNA in solution without transferring fragments to a membrane; Sanger sequencing determines the exact nucleotide sequence of a DNA fragment; RFLP refers to the polymorphism pattern itself—often detected by Southern blot, but not the transfer-and-probe step by itself.

So the described approach corresponds to Southern blotting.