Reasons to Believe: Should we Expect Efficiency Inside the Cell?

Jeff Zweerink, senior research scholar at Reasons to Believe, discusses the movement efficiency of Kinesin-1 in the context of a perceived design inefficiency in the reconnaissance aircraft SR-71.

Kinesin-1: The Cell’s Cargo Mover
Kinesin-1 moves vesicles around cells by “walking” along rod-like protein assemblies called microtubules (see video below). Kinesin-1 uses adenosine triphosphate (ATP) as fuel to move around. However, when a team of researchers at Yamaguchi University in Japan measured the motion of Kinesis-1 along the microtubules, they found that up to 80% of the energy released from ATP generated heat instead of movement!

When taking a quick look at the SR-71 blackbird and seeing it leaking fuel on the runway, you could draw a reasonable conclusion that the engineers had failed to design the aircraft well. However, a closer analysis reveals that the engineers intentionally designed the SR-71 blackbird in a way that would leak fuel on the ground. Flying at the incredible speeds the aircraft can achieve causes the fuel tanks to heat up and expand. If the tanks were sealed on the ground, the extreme heat during flight would make the tanks crack and explode. Stated another way, when the SR-71 fulfills its purpose in flight, all its components behave exactly as designed—even if it looks like failure when sitting on the runway.

In similar fashion, Kinesin-1 acts like a poorly designed molecule in the pristine conditions of the lab. However, when it operates in the noisy environment of the cell, it performs beautifully—just like it was designed to do.

See full article at Reasons to Believe

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