DNA finger printing:-

It is also called DNA typing or DNA profiling. A method of ascertaining relationship and the identity of person by means of DNA fingerprint which is unique to each individual.

Various steps:-

(i) DNA is extracted from the cell in a high speed refrigerated centrifuge.

(ii) If content is limited, it can be amplified by making many copies of it using PCR.

(iii) DNA is cut into fragements with site recognizing restriction enzymes for restriction fragment length anlysis.

(iv) Fragments DNA are introduced and passed through electrophors is set up containing agrose polymer gel separated fragments can be seen by staining with fluoresces under UV radiation.

(v) Double-standard DNA is then split into single standard DNA using alkaline chemicals.

(vi) Separated DNA sequences are them transferred to a nylon a nitrocellulose sheet placed over the gel. This is called 'southern blotting'.

(vii) The nylon sheet is them immersed in a bath and probes or markers that are radioactive synthetic DNA segments of known sequence are added. The probes target a specific nucleotide sequence which is complementary to VNTR sequence and hybridized them.

(viii) Finally, x-ray film is exposed to the nylon sheet containing radioactive probe dark band containing radioactive sites which resemble the bar codes.