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Ann Gauger June 11, 2014 5:32 AM
Perhaps you've seen the video from Discovery Institute of the miniature walking machine known as kinesin. This microscopic marvel gets the cell's protein products distributed to their final destinations, among other things.
This movement is extremely efficient, and by itself is a wonder.
But there's another wonder. A single kinesin can pull its cargo at up to 800 nanometers per second along its microtubule highway, depending on its load and the amount of ATP available. That's almost a micron per second. To give you a sense of scale, one bacterium is about a micron in length, and a typical animal cell is roughly 10 microns. That means that, under optimal conditions, and if kinesin is unobstructed, it could travel the length of an average cell in about 12.5 seconds. If it partners with other kinesin molecules, it can move even faster.
This is a good thing for our neurons. A neuron has its nucleus and its biosynthetic apparatus in the cell body. This is where proteins and organelles that the neuron needs are made. But these proteins and organelles are used out at the very tip of a long thin process called an axon, which extends from the body of the neuron all the way to the place it sends its signals.