Southern and Northern Blot Techniques,Molecular Weight,Endonucleases,Oligonucleotide,Agarose Gel,Electrophoresis

Southern and Northern Blot Techniques

Southern and Northern Blot Techniques
Southern blot is the classic technique described by Southern in 1975 for understanding individual genes in a complex mixture of DNA. The procedure involves cutting up high molecular weight genomic DNA into fragments by enzymatic digestion with restriction endonucleases. These bacterial enzymes have been isolated and are available in many laboratories.

The mechanism of protein synthesis

The Mechanism of Protein Synthesis

They have been prepared from several bacteria and are designed as molecular scissors which cut the strands of DNA at specific oligonuleotide recognition sequences

The fragments of DNA are then separated on the basis of size by agarose gel electrophoresis. The fragments with smaller number of nucleotides move faster on the gel in an electric current than the larger ones which have higher number of nucleotides.

At the end of the experiment, the gel is immersed in a fluorescent dye (ethidium bromide) which binds to DNA. When viewed under ultra-violet light, the fragments can be visualized as separate entities reflecting the nucleic acid pattern.

The cellular RNA can also be run on agarose gel and the fragments can be separated in much the same way as DNA. This technique is known as Northern blot technique.

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Southern and Northern Blot Techniques