What is hybridization / blotting?

Blotting of nucleic acid is the central technique for hybridization studies. Double stranded DNA will denature or separate at high temperatures into single strands. When the temperature is lowered, the two strands will anneal because of the base pairing interaction between the complementary strands. If nucleotide sequences are identical or similar, complementary strands from different sources will anneal. This is called hybridization to indicate that each strand of DNA came from a different source.

The single strands that hybridize to one another to form double stranded DNA are homologous (have similar or identical nucleotide sequences). This high specificity of base pairing interaction between complementary strands of DNA can be used to locate specific nucleotide sequences in a sample. The DNA from one source can be immobilized by attachment to a solid surface. Homologous DNA from another source will hybridize to the immobilized DNA.  Non-homologous DNA will not bind / attach. This is the basis of DNA probe techniques. A probe is a piece of DNA with a specific nucleic acid sequence that is labelled with a marker which allows identification and quantification.