Reported June 2006

BACKGROUND: Using satellite images for an initial design, artist Liz Hickok built a scale model of San Francisco using nothing but molded Jell-O, which was featured at the Exploratorium Science Museum. The jiggling mini-city was mounted on Plexiglass and placed on a shake table to simulate what happens to buildings during an earthquake. Specifically, it demonstrates liquefaction, when tremors pressurize the water in soil underneath a building.

WHAT IS GELATIN? Gelatin is a processed protein called collagen, derived from the bones, hooves and connective tissues of cows or pigs. Those parts are ground up and mixed with acid or other chemicals to break down the cellular structure, thereby releasing the collagen. Boiling it causes a layer of gelatin to form on the top, which can be skimmed off for further processing. Eventually it ends up in your local grocery store aisle in powder form.

HOW IS JELL-O LIKE DNA? Different proteins have different structures. Gelatin's structure is similar to DNA, except where DNA has two chains twisted together into a helix, the proteins that make up gelatin have three chains of amino acids tightly bonded together. The only thing that breaks those bonds is energy. Boiling water adds a great deal of energy, in the form of heat, sufficient to cause the three strands of amino acids in collagen to unwind. As gelatin cools, the chains start bonding again.

WHY IT GELS: Because it takes so long to cool, the amino acid chains become entangled as the mixture is stirred, and water gets into gaps between the chains. You can add ice so the gelatin will set more quickly, but it is never quite as firm as that produced by the slow-set method. The various molecules cool so quickly that they can't self-organize in the most efficient and strongest bonds possible; instead, only a loose matrix forms. If the energy levels of the requisite molecules are lowered more gradually, as in the slow-setting method, they have more time to align properly, forming a much denser lattice structure, trapping the mixture of sugar, pigments and water in between the strands of amino acids.

The Incorporated Research Institutions for Seismology, Inc., contributed to the information contained in the TV portion of this report.

If you would like more information, please contact:

Eric Muller
Earth Scientist
Exploratorium
emuller@exploratorium.edu

For more information about the science of seismology:

John Taber
Education & Outreach Program Manager
Incorporated Research Institutions for Seismology
Washington, DC 20005
(202) 682-2220
taber@iris.edu

FACTOID...

Scientists found adding stem cells to spinal implants made of hydrogels can help patients with old injuries regain a certain degree of function. The gels resemble the soft tissue that surrounds the human spinal cord as it develops in the womb. The hydrogel fills the spaces in the injured areas, creating a kind of scaffolding new cells can grow around, building a bridge of sorts to repair the damage.

ON THE WEB...

Artist Liz Hickok