What are the differences between Northern blot, Southern blot and Western blot?

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Accepted Answer

Blotting techniques are commonly used to identify and separate a target molecule from a complex mixture of molecules. While they all follow a similar type of workflow, each blotting technique differs in the type molecule it can identify. The following table outlines the differences between each blotting technique.

Technique 
Western Blot
Northern Blot
Southern Blot

Target Molecule
Protein
RNA
DNA

Sample Prep
Protein extraction
RNA isolation
DNA extraction

Separation 
Gel Electrophoresis/SDS-PAGE
Gel Electrophoresis
Gel Electrophoresis

Membrane Material 
Nitrocellulose/PVDF
Nylon
Nylon

Probe
Uses a single primary antibody or a combination of primary and secondary antibodies conjugated to either a fluorophore or enzyme
 RNA, DNA or oligodeoxynucleotide
 Nucleic acid probe

Detection
Film, CCD camera, LED or infrared imaging system
 X-Ray film, chemiluminescence
 X-Ray film, chemiluminescence

Technique	Western Blot	Northern Blot	Southern Blot
Target Molecule	Protein	RNA	DNA
Sample Prep	Protein extraction	RNA isolation	DNA extraction
Separation	Gel Electrophoresis/SDS-PAGE	Gel Electrophoresis	Gel Electrophoresis
Membrane Material	Nitrocellulose/PVDF	Nylon	Nylon
Probe	Uses a single primary antibody or a combination of primary and secondary antibodies conjugated to either a fluorophore or enzyme	RNA, DNA or oligodeoxynucleotide	Nucleic acid probe
Detection	Film, CCD camera, LED or infrared imaging system	X-Ray film, chemiluminescence	X-Ray film, chemiluminescence

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