So obviously, viruses are nonliving. But when my teacher was teaching viruses in the video (we're doing "flip" learning this semester), the way he described it, it seemed like the viruses responded to their environment in that they moved around until they found a cell of the right type, and then they latched on and hijacked it.
I had always thought of it more like that they were just kind of floating around, carried by the bloodstream (when in an animal/plant), until they "bumped into" the right kind of cells and both sets of membrane proteins "docked". But my theory/idea doesn't really make sense because it doesn't account for how viruses would be able to infect bacteria.
But, the idea that viruses propel themselves doesn't make much sense either, because viruses are nonliving, and one of the characteristics of life that they do not meet is that living things acquire and use energy.
So I guess my question is, how are viruses propelled? Do they move themselves, or are they moved by external forces?