In which type of blotting is cDNA primarily used as a probe?

cDNA, or complementary DNA, is primarily used as a probe in Northern Blotting. This technique is specifically designed for the detection of RNA molecules, allowing researchers to study gene expression. Since cDNA is synthesized from mRNA through reverse transcription, it serves as an ideal probe to relate to RNA and can hybridize effectively to the target RNA present in the sample.

In a Northern Blot procedure, total RNA is extracted from a sample, separated by gel electrophoresis, and then transferred to a membrane. The cDNA probes are used to bind to specific mRNA sequences on the membrane, providing information about the abundance and size of particular mRNAs, which reflects the expression levels of the corresponding genes in the sample.

The other techniques mentioned have different probes and targets; Southern Blots use DNA probes for DNA detection, while Western Blots utilize antibodies to target proteins. Hybridization Blot is too general and does not specifically imply cDNA usage as it may refer to various blotting techniques. Therefore, Northern Blotting is distinctly associated with the use of cDNA probes to analyze RNA.