DNA Fingerprinting Steps Sequence Explained

Understanding the correct order of steps in DNA fingerprinting is crucial for accurate analysis. The process involves several key stages, from extracting DNA to detecting specific fragments.

Correct Sequence of DNA Fingerprinting Steps

The standard procedure for DNA fingerprinting follows this sequence:

1. Step A: Isolation of DNA and its digestion by restriction endonucleases. This initial step involves collecting a biological sample (like blood or saliva) and extracting the DNA. The DNA is then cut into smaller fragments using specific enzymes called restriction endonucleases.
2. Step E: Separation of DNA fragments by electrophoresis. The digested DNA fragments are separated based on their size using a technique called gel electrophoresis. Smaller fragments move further down the gel than larger ones.
3. Step C: Transferring of separated DNA fragments to synthetic membranes. The separated DNA fragments on the gel are transferred onto a solid support, typically a nylon membrane, through a process similar to Southern blotting. This makes the fragments easier to analyze.
4. Step B: Hybridisation using a labelled VNTR probe. The membrane is exposed to a radioactive or fluorescently labelled probe. This probe is designed to bind specifically to variable number tandem repeat (VNTR) regions within the DNA fragments, which are unique to individuals.
5. Step D: Detection of hybridised DNA fragments by autoradiography. Finally, the locations where the labelled probe has bound to the DNA fragments on the membrane are visualized. This is often done using autoradiography (if radioactive probes are used) or other detection methods, revealing the unique pattern of DNA fragments – the DNA fingerprint.

Therefore, the correct sequence is A, E, C, B, D.