When a gene (not the entire chromosome) is in a low abundance, this quantity of the gene can be amplified in an exponential manner. Taq polymeraise, a biological machine (often in the form of PCR beads) is added to the DNA sample. The tube with DNA solution is placed into a PCR machine, like the Revolutionary Science RevCycler. During the 94 Celsius denature phase, the DNA ladder denatures (separates into two half ladders) and the temperature of of the PCR machine drops to the anneal temperature (usually between the temperature of 40 to 60 Celsius), so the RNA primers can attach to the gene of interest.
The next step is extend at 72 Celsius, where the RNA primers are removed and replaced with single stranded DNA, to complete two new DNA ladders. This process is repeated. Each cycle doubles the original amount of DNA. This usually continues for about 35 cycles. When the DNA is amplified it can be left in the RevCycler where it will automatically change temperature to a 4 degree Celsius refrigeration temperature hold. Amplified DNA can be stored in a freezer until analysis. Analysis can be performed with DNA electrophoresis chamber like the DNA RevBox.