Einstein Science Reporting for Kids
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20-Aug-2004

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Freight-carrying proteins vibrate walls of cells



Close-up of an atomic force microscope image of yeast cells. The arrow points to a bud scar on the cell surface. Image Science.
Click here for a high resolution photograph.

Like passing freight trains that shake the walls of nearby houses, cargo-carrying proteins shake the cell walls of yeast.

The scientists measured these tiny cell wall vibrations in the kind of yeast used to make bread rise. They performed many experiments to try to understand what makes the cell walls vibrate. They think that the freight carriers, also called molecular motors, cause the wall vibrations as they carry everything from protein bits to whole chromosomes through the cell.

Since sound is created by vibrations, the scientists also figured out what the cell wall movements would sound like if you could hear them.

If a yeast cell were the size of human, its vibration noise wouldn't sound like someone blasting loud music.



Close-up of an atomic force microscope image of a yeast cell trapped in a tiny hole. Image Science.
Click here for a high resolution photograph.

"It would sound more like someone listening to news quietly," said scientist James Gimzewski from University of California - Los Angeles in Los Angeles, California.

Gimzewski thinks sound is an interesting way to present observations of vibrating cell walls. The movements are too small and fast to be seen on video.

To investigate why the cells vibrate, the scientists studied the vibrations at different temperatures. They also treated yeast cells with a chemical that prevents the cells from producing energy.



Bioscope atomic force microscope used to measure motions of yeast cells. Image courtesy of PicoLab UCLA.
Click here for a high resolution photograph.

The vibrations stopped when the cells stopped producing energy.

From these and a few other experiments and calculations, the scientists say that cell wall motion in yeast is probably caused by the activity of many molecular motors working within the cell at the same time.

The scientists think these movements might be useful to the yeast cells. The motion could be part of a communication pathway or a pumping action that helps move nutrients or chemicals from one side of the cell wall to the other. This research paper appears in the 20 August 2004 issue of the journal Science.

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Q & A: A related Q & A with a kid and the corresponding author.

Additional images and audio files are available at a password protected site provided by the PicoLab UCLA. Please note that this material is under strict embargo until Thursday, 19 August 2004, 2 PM US ET.

http://www.chem.ucla.edu/dept/Faculty/gimzewski/teapot/

password: chittychittybangbang

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