Size: Most bacteria fall within a range from 0.2 to 2.0 um in diameter and from 2 to 8 um in length A rod-shaped prokaryote is typically about 1-5 micrometers (μm) long and about 1 μm wide Microorganisms in general are very small and are completely invisible to the naked eye. A cyanobacterium 8 x 50 umSize: Most bacteria fall within a range from 0.2 to 2.0 um in diameter and from 2 to 8 um in length A rod-shaped prokaryote is typically about 1-5 micrometers (μm) long and about 1 μm wide Microorganisms in general are very small and are completely invisible to the naked eye. A cyanobacterium 8 x 50 um