Word: flagella
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OPTICAL TWEEZERS. With a single beam of infrared laser light, scientists can seize and manipulate everything from DNA molecules to bacteria and yeast without harming them. Among other things, optical tweezers can keep a tiny organism swimming in place while scientists study its paddling flagella under a microscope. Optical tweezers can also reach right through cell membranes to grab specialized structures known as organelles and twirl them around. Currently, researchers are using the technology to measure the mechanical force exerted by a single molecule of myosin, one of the muscle proteins responsible for motion. Scientists are also examining the swimming...
Biochemists Robert M. Macnab and Daniel Koshland were investigating a characteristic that S. typhimurium shares with many other bacteria: it responds strongly to changes in external stimuli. If, for instance, a hostile substance is introduced into its surroundings, the bacterium uses its flagella -long, hairlike appendages-to swim away from it. But if something attractive is placed near by-say, the sugar, glucose-it will move toward it. How the bacterium chooses its direction is still not fully understood, but it apparently makes its way on a trial-and-error basis. Tumbling to and fro, it senses that taking certain...
...Bacteria are far from being homogeneous globs of matter. The micrographs clearly show membranes, nuclei, sometimes surrounding capsules and whiplike appendages called flagella. Some of these details had been seen with ordinary microscopes, but many were unsuspected...
...headed vulture, which had swooped upon a spectacled owl, which had clenched (and been hugged dead by) an anaconda, which had bolted a basha (torpedo-shaped fish), which had snapped up a pok-poke (smoky jungle frog), in whose food canal lived an opalina (irridescent protozoan covered with hairlike flagella). Explorer William Beebe, who fired the shotgun, indicates this chain of life with his dissecting knife, philosophizing as he studies Nature in the steaming jungle of British Guiana. Other chapters-creeping, rustling, whirring, crashing, oozing with live things-centre on an inverted, deaf, lethargic, odorless, whistling sloth; the falling...