Northern Blotting Analysis

Northern Blotting Analysis is a procedure used to detect a specific RNA molecule/specific group of RNA molecules within a larger group of RNA molecules. It is commonly used in research to study gene expression. It is similar to the Southern blotting Analysis, but detects RNA rather than DNA. First, RNA molecules are extracted, usually from cells. The RNA molecules are then separated by gel electrophoresis, which separates them based on their size. RNA molecules have a negative charge, so they travel towards the positive side. The smaller molecules will travel faster and thus, the molecules will end up in an order than ranges from big to small, from negative to positive. The gel that is used is a formaldehyde gel which denatures the RNA so that it is single-stranded rather than double stranded, so that it can be effectively probed later on. Next, a blotting procedure is used to transfer the RNA from the gel to a membrane, in which the RNA can be probed. The last major step is the probing/hybridization, where a DNA molecule (usually cDNA) with a sequence that is complementary to the desired RNA strand, is used to probe the RNA. Then the excess probes are washed off so that the results can be visualized in an autoradiograph.