The Biological Motors That Power Our Bodies
Most of us will probably be able to recall at least vaguely that a molecule called ATP is essential for making our bodies move, but this molecule is only a small part of a much larger system. Although we usually aren’t aware of it, our bodies consist of a massive collection of biological motors and related structures, which enable our muscles to contract, nutrients and fluids to move around, and our cells to divide and prosper. Within the biochemical soup that makes up single- and multi-cellular lifeforms, it are these mechanisms that turn a gooey soup into something that can do much more than just gently slosh around in primordial puddles.
There are many similarities between a single-cell organism like a bacteria and eukaryotic multi-cellular organisms like us humans, but the transition to the latter requires significantly more complicated structures. An example for this are cilia, which together with motor proteins like myosin and kinesin form the foundations of our body’s basic functioning. Quite literally supporting all this is the cytoskeleton, which is a feature that our eukaryotic cells have in common with bacteria and archaea, except that eukaryotic cytoskeletons are significantly more complex.
Image of the mitotic spindle in a human cell showing microtubules in green, chromosomes (DNA) in blue, and kinetochores in red. “Kinetochore” by [Afunguy].We mammals have a skeleton to keep our bodies from collapsing into a sad, soggy pile, so too do our cells have their own skeleton, giving them shape and rigidity, as well as providing motor proteins something to interact with. The cytoskeleton in eukaryotes consists of mainly microfilaments, intermediate filaments and microtubules, with prokaryotes having their own distinct cytoskeleton structures. Of the three types that make up the eukaryotic cytoskeleton, the microfilament and microtubules are used by motor proteins. These thus fall into two categories: actin motors (using the actin-based microfilaments) and microtubule motors.
