Son-of-Son-of-Cycle, Thermal Cycler

Description (Brief)
This object, nicknamed “Son of Son of Cycle,” was the third prototype automated PCR machine developed by engineers at Cetus.
PCR, short for polymerase chain reaction, was a revolutionary laboratory technique developed by Kary Mullis at Cetus Corporation in 1983. PCR acts like a photocopier for genetic material, working on principals similar to nature’s own method for replicating DNA. With the reaction, scientists can take a single portion of DNA they wish to study and amplify it into millions of copies in only a few hours. This simple technique for creating large amounts of DNA resulted in huge leaps in genetic research in a variety of fields from evolutionary biology to forensics to medicine.
Although the reaction is straightforward, requiring only a few ingredients, it is incredibly time-consuming to perform by hand. Because different steps of the reaction take place at different temperatures (hence the name “thermal cycling”), scientists performing the reaction were required to stand at the lab bench for several hours, moving the sample back and forth between water baths of different temperatures. While they loved the technique, scientists were eager for an automated machine that could perform the reaction for them.
“Son of Son of Cycle” is very similar to the second prototype PCR machine “Son of Cycle,” consisting of a control box (with the digital display) and a reagent box (with wells on top for sample tubes where the reaction took place). Sample tubes containing all the reagents necessary for the reaction were placed in the wells on top of the reagent box. The duration of the cycle would be programmed using the control box and the changes in temperature occurred through Peltier devices for thermoelectric heating and cooling. Like “Son of Cycle,” “Son of Son of Cycle” utilized heat-stable enzymes, chemicals used to speed up the reaction. (Early on, enzymes that were not heat-stable were used in PCR. Because they were degraded at high temperature, new enzyme had to be added with every cycle.) This prototype was an improvement over the previous prototype because it incorporated more Peltier devices, allowing for a greater number of samples in a single run. It also used a different path for airflow, resulting in a more efficient cooling system.
Currently not on view
Object Name
thermal cycler
Physical Description
metal (overall material)
plastic (overall material)
insulated wire (overall material)
average spatial: 33.6 cm x 33 cm x 45.7 cm; 13 1/4 in x 13 in x 18 in
ID Number
catalog number
accession number
See more items in
Medicine and Science: Biological Sciences
Science & Mathematics
Biotechnology and Genetics
Polymerase Chain Reaction (PCR)
Data Source
National Museum of American History, Kenneth E. Behring Center


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