Question

For which of these is northern blotting with hybridization useful?

• A. Protein antigen
• B. RNA
• C. DNA
• D. Histone

Hint:

Remember the naming pattern: Southern blot detects DNA, northern blot detects RNA, and Western blot detects protein using antibodies.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks which type of molecule is picked up when northern blotting is combined with hybridization.

Step 2: Key Concept:
Blotting techniques in molecular biology are named for the molecule each one detects. Southern blotting, named after its inventor Edwin Southern, detects DNA. Northern blotting is the RNA version of the same idea, built on the same steps but applied to RNA. Western blotting detects protein, using labeled antibodies instead of a nucleic acid probe.

Step 3: Detailed Explanation:
In northern blotting, RNA is first extracted from the sample and separated by size on a gel using electrophoresis.
The separated RNA bands are then transferred, or blotted, onto a nylon or nitrocellulose membrane.
A labeled probe, either a DNA or RNA strand whose sequence is complementary to the RNA of interest, is added and allowed to hybridize, meaning it binds the matching RNA band by base pairing.
This tells the lab whether a specific messenger RNA is present in the sample, and roughly how much of it there is, which is why northern blotting is a standard tool to study gene expression.

Step 4: Final Answer:
Protein antigen is picked up by Western blotting using antibodies, since a protein has no base sequence to hybridize with. DNA is the target of Southern blotting, not northern blotting. Histone is a DNA binding protein, so like any protein it needs Western blotting or an immunological method, not hybridization. Northern blotting with hybridization is useful for detecting RNA.