Southern blot

A laboratory technique that detects specific DNA sequences by separating DNA fragments, transferring them to a membrane, and hybridizing them with a labeled probe.

Restriction enzyme: An enzyme that cuts DNA at or near a specific nucleotide sequence. Restriction enzymes create the DNA fragments separated before transfer.
DNA: A molecule that stores hereditary information in most organisms, usually as two complementary nucleotide strands. Southern blotting detects sequences within this molecule.
Edwin Southern: A British molecular biologist who developed the DNA blotting method named after him. His 1975 method established the procedure for detecting specific DNA fragments.
Restriction fragment length polymorphism: A DNA variation that changes the lengths of fragments produced by restriction enzymes. Southern blots can reveal these inherited length differences as distinct band patterns.
Polymerase chain reaction: A laboratory method that amplifies a selected DNA region through repeated cycles of DNA synthesis. PCR detects or amplifies chosen sequences without transferring genomic fragments to a membrane.
Agarose gel electrophoresis: A method that separates DNA molecules by size as they move through an agarose gel in an electric field. It sorts restriction fragments by length before they are blotted.
DNA probe: A labeled DNA or RNA strand designed to bind a complementary target sequence. The probe supplies the sequence specificity that identifies a target fragment.
DNA blotting: A family of laboratory methods that transfer DNA from a gel to a membrane for detection or analysis. Southern blotting became the prototype for membrane-based blotting methods.
DNA fingerprinting: The identification of individuals by comparing characteristic patterns of variable DNA regions. Early DNA fingerprinting used Southern blots to visualize variable repeat-containing fragments.
Quantitative PCR: A PCR method that measures DNA amplification in real time using fluorescent signals. It quantifies target DNA more rapidly but usually does not show its restriction-fragment context.

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