Question

Arrange the following steps of DNA fingerprinting in correct sequence :

Gel electrophoresis
Isolation of DNA
Southern blotting
Restriction digestion

Hint:

A mnemonic to remember the core steps: \textbf{I}ce \textbf{D}rink \textbf{E}very \textbf{S}ummer. (\textbf{I}solation, \textbf{D}igestion, \textbf{E}lectrophoresis, \textbf{S}outhern blotting).

Answer 1

The correct sequence for the steps of DNA fingerprinting is:

1. Isolation of DNA (b): DNA is extracted from the cells of a biological sample (like blood, saliva, or hair).
2. Restriction digestion (d): The isolated DNA is cut into smaller fragments using restriction enzymes.
3. Gel electrophoresis (a): The DNA fragments are separated according to their size by running them through an agarose gel. Smaller fragments move faster and further.
4. Southern blotting (c): The separated DNA fragments are transferred (blotted) from the gel onto a nylon membrane.

The correct sequence is: (b) $\rightarrow$ (d) $\rightarrow$ (a) $\rightarrow$ (c)

Explanation:

DNA fingerprinting involves a series of steps to analyze genetic material. The process begins by isolating the DNA from the sample. Next, restriction enzymes are used to cut the DNA into smaller fragments. These fragments are then separated by size using gel electrophoresis, where smaller fragments move faster than larger ones. Finally, Southern blotting is used to transfer the separated DNA fragments onto a membrane, where they can be analyzed further, often using a probe to identify specific sequences.

Conclusion:

The correct sequence for DNA fingerprinting involves the following steps: (b) Isolation of DNA, (d) Restriction digestion, (a) Gel electrophoresis, and (c) Southern blotting.