Electrophoresis Tank, Model LT48-A

Description (Brief)
Carl Woese, a microbiologist and evolutionary biologist, used this electrophoresis tank in pioneering research on the evolution of bacteria. His work established that evolutionary relationships between organisms could be found using genetic differences, not just morphology (the way they look).
Woese made his career at the University of Illinois at Urbana-Champaign where early on he searched for a way to classify species of bacteria. In the early 1960s, scientists developed evolutionary trees mainly by comparing species' morphological differences. Simple, single-celled organisms like bacteria, however, lack the complex morphology necessary for this kind of comparison.
A molecular biologist by training, Woese looked to differences in the chemical makeup of bacteria to help classify them. Woese chose ribosomal RNA (rRNA) as his molecule of comparison, specifically a section of the rRNA called the 16S portion. Ribosomal RNA made a good target molecule for several reasons. Most importantly, its sequence (the order of its individual molecules) tends to be highly conserved. This means that there is not a wide variety of changes over time or between species, so there are a smaller number of differences to compare between organisms. What’s more, all living things contain rRNA, therefore it can be used to compare any two species. Finally, it’s relatively easy to extract from cells.
Woese's team for the project included Ralph S. Wolfe, George E. Fox, William E. Balch, Kenneth R. Luehrsen, and Linda J. Magrum. In the lab, they cut the rRNA into small fragments and sequenced the shorter fragments. Next, they searched for differences in the sequences between bacterial species. Part of this work entailed separating fragments from one another according to their electrical charges. The task was completed using this electrophoresis tank. The team’s findings suggested that comparing molecular differences between species was indeed an effective way to discern evolutionary relationships. What’s more, they discovered that some of the bacterial species were so distinct from others that they necessitated a new branch on the tree of life—“Archaea.” At the time, scientists divided life between just two branches—prokaryotes and eukaryotes.
At first the larger scientific community was skeptical of the Archaea addition. With time and growing evidence through the 1980s, however, they accepted Woese’s findings. Today, genetic and molecular comparisons between species are the primary tool for figuring out evolutionary relationships.
Collections Committee Memo, Accession File 2013.0281, National Museum of American History.
Virginia Morell, “Microbiology's Scarred Revolutionary,” Science 276, no. 5313 (1997): 699–702.
Norman R. Pace, Jan Sapp, and Nigel Goldenfeld, “Phylogeny and beyond: Scientific, historical, and conceptual significance of the first tree of life,” Proceedings of the National Academy of Sciences 109, no. 4 (2012): 1011–18.
Exhibition Booklet, Uncovering Life’s Third Domain: The Discovery of the Archaea, The Institute for Genomic Biology and the Spurlock Museum, University of Illinois at Urbana-Champaign.
Carl Woese et al., “A Comparison of the 16S Ribosomal RNAs from Mesophilic and Thermophilic Bacilli: Some Modifications in the Sanger Method for RNA Sequencing,” Journal of Molecular Evolution 7, no. 3 (1976): 197–213.
Currently not on view
Object Name
electrophoresis tank
date used
Physical Description
metal (overall material)
lucite (overall material)
overall: 27 in x 28 in x 12 in; 68.58 cm x 71.12 cm x 30.48 cm
ID Number
catalog number
accession number
model number
Model LT48-A
serial number
Science & Scientific Instruments
See more items in
Medicine and Science: Biological Sciences
Science & Mathematics
Biotechnology and Genetics
Data Source
National Museum of American History, Kenneth E. Behring Center


Add a comment about this object