Question

Arrange the given steps of DNA fingerprinting in the sequence from initiation to end:
(A) Digestion of DNA by restriction endonuclease
(B) Isolation of DNA
(C) Hybridisation using labelled VNTR probe
(D) Transferring (blotting) of separated DNA fragments to synthetic membrane
Choose the correct answer from the options given below:

• A. (A), (B), (C), (D)
• B. (A), (D), (C), (B)
• C. (B), (A), (D), (C)
• D. (C), (A), (B), (D)

Answer 1

The Correct Option is C

The process of DNA fingerprinting involves several sequential steps. Understanding the correct order is critical for accurate results. Below are the steps explained in the order they are performed: 

1. Isolation of DNA: The initial step is to extract DNA from cellular material. This involves breaking open cells and using chemical procedures to purify the DNA, free from proteins and other contaminants.
2. Digestion of DNA by restriction endonuclease: Once isolated, the DNA is cut into fragments using restriction enzymes known as endonucleases. These enzymes recognize specific sequences and cleave the DNA at these sites, resulting in a mixture of smaller DNA fragments.
3. Transfer (blotting) of separated DNA fragments to synthetic membrane: The fragmented DNA is then separated based on size by gel electrophoresis. These fragments are transferred onto a synthetic membrane, a process called blotting, where they are immobilized.
4. Hybridisation using labelled VNTR probe: The membrane with immobilized DNA fragments is exposed to VNTR (Variable Number Tandem Repeats) probes that have been labelled. These probes hybridize to specific DNA sequences, and their patterns can be visualized using suitable detection methods.

This sequence is represented by option: (B), (A), (D), (C).

Answer 2

(B) Isolation of DNA

The first step in DNA fingerprinting is the isolation of DNA from the biological sample. This involves extracting DNA from cells.

(A) Digestion of DNA by restriction endonuclease

After isolating the DNA, it is digested using restriction endonucleases. These enzymes cut the DNA at specific sequences, resulting in fragments of various sizes.

(D) Transferring (blotting) of separated DNA fragments to synthetic membrane

The digested DNA fragments are then separated by size using gel electrophoresis. After separation, the DNA fragments are transferred (blotted) onto a synthetic membrane.

(C) Hybridisation using labelled VNTR probe

Finally, the transferred DNA fragments on the membrane are hybridized with a labelled VNTR (Variable Number Tandem Repeat) probe. This probe binds to specific sequences in the DNA, allowing the visualization of the unique pattern of DNA fragments.

Conclusion

The correct sequence of steps in DNA fingerprinting is:

• (B) Isolation of DNA
• (A) Digestion of DNA by restriction endonuclease
• (D) Transferring (blotting) of separated DNA fragments to synthetic membrane
• (C) Hybridisation using labelled VNTR probe

Therefore, the correct answer is (3) (B), (A), (D), (C).