Arrange the following steps of DNA fingerprinting in a correct sequence.

A. Isolation of DNA and its digestion by restriction endonucleases.
B. Hybridisation using a labelled VNTR probe.
C. Transferring of separated DNA fragments to synthetic membranes.
D. Detection of hybridised DNA fragments by autoradiography.
E. Separation of DNA fragments by electrophoresis.

Choose the correct answer from the options given below :

The correct sequence of steps in DNA fingerprinting is **A, E, C, B, D**.

Step A – Isolation of DNA and its digestion by restriction endonucleases
The process begins with extracting genomic DNA from the sample (blood, hair, etc.). The extracted DNA is then cut with specific restriction enzymes that recognize short DNA sequences and cleave the DNA at those sites. This produces a mixture of DNA fragments of varying lengths that contain the variable number tandem repeat (VNTR) regions used for fingerprinting.

Step E – Separation of DNA fragments by electrophoresis
The digested fragments are loaded onto an agarose gel and subjected to an electric field. Because DNA is negatively charged, fragments migrate toward the positive electrode; smaller fragments travel faster than larger ones. This step resolves the mixture into distinct bands representing fragments of different lengths.

Step C – Transferring of separated DNA fragments to synthetic membranes
After electrophoresis, the DNA bands are transferred from the gel onto a durable nylon or nitrocellulose membrane in a process called Southern blotting. The transfer preserves the spatial order of the fragments and makes them accessible for probing.

Step B – Hybridisation using a labelled VNTR probe
A DNA probe that is complementary to the VNTR region is labelled (radioactively or with a fluorescent tag). The membrane is incubated with this probe, allowing it to hybridise (bind) to fragments that contain the VNTR sequences. Only the fragments with complementary VNTRs retain the label.

Step D – Detection of hybridised DNA fragments by autoradiography
Finally, the membrane is placed against an X‑ray film (or a phosphor screen) to detect the labelled probe. The exposed film reveals a pattern of dark bands corresponding to the VNTR‑containing fragments. This banding pattern constitutes the DNA fingerprint of the individual.

Putting the steps together gives the logical flow: isolate and cut DNA (A), separate fragments by size (E), blot the fragments onto a membrane (C), hybridise with a labelled probe (B), and visualise the hybridised fragments (D). This ordering matches option **A, E, C, B, D** and not any of the other permutations.