A better way to count molecules discovered

Researchers at the Swedish medical university Karolinska Institutet have developed a new method for counting molecules. Quantifying the amounts of different kinds of RNA and DNA molecules is a fundamental task in molecular biology as these molecules store and transfer the genetic information in cells. Thus, improved measurement techniques are crucial for understanding both normal and cancer cells. It is very difficult to detect small individual molecules in a complex mixture. Therefore, the signal is usually first amplified by making many copies of each molecule. Unfortunately, the copying complicates tracking the exact number of original molecules. The reason is that it is virtually impossible to tell afterwards exactly how many times each original molecule was copied as all copies originating from same type of molecules are indistinguishable from each other.