Picking out a piece of DNA
Scientists can pick out a particular piece of DNA on the nylon membrane using a DNA probe. The average DNA probe is about 1000 letters long. Scientists tag the probe with either a chemical dye or radioactivity so they can see it. Then they heat it so that it unzips into two separate strands. Finally it is washed over the membrane. The unzipped DNA probe sticks to any matching pieces of DNA on the membrane by a process called DNA hybridisation.