Question

Arrange the below given steps of DNA fingerprinting in sequence by selecting the appropriate option.
a) Digestion of DNA by restriction endonucleases
b) Autoradiography
c) Blotting of DNA fragments to nitrocellulose membrane
d) Isolation of DNA
e) Separation of DNA fragments by electrophoresis

• A. (a), (e), (d), (c), (b)
• B. (e), (a), (d), (b), (c)
• C. (d), (a), (e), (c), (b)
• D. (c), (b), (a), (e), (d)

Hint:

Follow the logical physical flow: Isolate it $\rightarrow$ Cut it $\rightarrow$ Separate it $\rightarrow$ Transfer it $\rightarrow$ Photograph it.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept: DNA fingerprinting is an advanced laboratory technique used to establish a link between biological evidence and a suspect, involving a highly specific series of molecular biology steps.
Step 2: Key Formula or Approach: Arrange the laboratory procedures logically from the initial collection of the raw sample to the final visualization of the results.
Step 3: Detailed Explanation: The process developed by Alec Jeffreys follows a precise chronological order:
1. First, you must obtain the raw genetic material. This is the Isolation of DNA (step d).
2. The long, continuous DNA strands are then cut into smaller, manageable fragments using specific enzymes. This is the Digestion of DNA by restriction endonucleases (step a).
3. These fragments of varying sizes need to be sorted. This is achieved by Separation of DNA fragments by electrophoresis (step e).
4. The separated DNA bands on the fragile agar gel are then transferred to a much sturdier medium. This is the Blotting of DNA fragments to synthetic membranes like nitrocellulose or nylon (step c).
5. After hybridization with a radioactive probe, the final step is to capture the image of the bands on an X-ray film. This is called Autoradiography (step b).
Therefore, the correct chronological sequence is d $\rightarrow$ a $\rightarrow$ e $\rightarrow$ c $\rightarrow$ b.
Step 4: Final Answer: The correct sequence matches option (3).