Question

In Northern hybridization?

• A. DNA sample is immobilized on the membrane
• B. RNA sample is immobilized on the membrane
• C. Copy number of transgene can be known
• D. Can be used only for transgenic characterization

Hint:

Remember the classic blotting triad:
- Southern Blotting $\rightarrow$ Detects DNA.
- Northern Blotting $\rightarrow$ Detects RNA.
- Western Blotting $\rightarrow$ Detects Proteins.
(Mnemonic: Snow Drop, New Rose, Wet Plant).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Northern hybridization (Northern blotting) is a classic molecular biology technique used to detect specific RNA molecules within a complex mixture of total RNA or messenger RNA.
It is widely used to analyze gene expression patterns by measuring the size and abundance of transcripts.

Step 2: Detailed Explanation:
Let us analyze the steps and characteristics of Northern hybridization:
- In Northern blotting, total RNA or mRNA samples are first separated based on size using agarose gel electrophoresis (typically under denaturing conditions containing formaldehyde).
- The separated RNA bands are then transferred (blotted) and immobilized onto a nylon or nitrocellulose membrane via capillary action or vacuum transfer.
- After immobilization, the membrane is hybridized with a labeled, sequence-specific DNA or RNA probe to detect the target transcript.
Let us evaluate why the other options are incorrect:
- Option (A): Describes Southern hybridization, where DNA samples are separated and immobilized on a membrane to detect specific DNA sequences.
- Option (C): Southern hybridization (not Northern) is used to determine the integration and copy number of a transgene in the host genome.
- Option (D): Northern blotting is a general molecular biology tool used to study gene expression across diverse research areas, not restricted solely to transgenic plant characterization.
Therefore, Northern hybridization is characterized by immobilizing RNA samples on the membrane.

Step 3: Final Answer:
In Northern hybridization, the RNA sample is immobilized on the membrane.