Southern blotting workflow Which description best summarizes the core steps of a Southern blot used to detect specific DNA sequences?

Introduction / Context:Southern blotting is a classic technique for detecting specific DNA fragments after restriction digestion and gel electrophoresis, using hybridization with a labeled probe.

Given Data / Assumptions:

• Target nucleic acid is DNA.
• Fragments are separated on an agarose gel.
• Transfer to a membrane enables stable probe hybridization.

Concept / Approach:The method proceeds: digest DNA, electrophorese, depurinate/denature, transfer (capillary or electroblot) to a membrane, fix DNA, hybridize with labeled probe, wash, and detect.

Step-by-Step Solution:Run DNA on agarose gel to resolve sizes.Denature and transfer DNA to a membrane (nylon/nitrocellulose).Hybridize with a complementary labeled DNA/RNA probe.Wash and visualize by autoradiography or chemiluminescence.

Verification / Alternative check:Controls with known positive and negative fragments confirm specificity and size.

Why Other Options Are Wrong:Options involving RNA describe Northern blotting; skipping transfer prevents durable detection; proteins correspond to Western blots.

Common Pitfalls:Poor transfer efficiency; nonstringent washes causing background; probe mishybridization.

Final Answer:Electrophoresis of DNA molecules and then blotting the separated DNA bands followed by incubation.