Biology / Unit 9 Bio 1943 short lesson, about 20 seconds
Three Prokaryotic Cell Shapes
Captions available
The idea
Prokaryotic cells fall into three basic shapes: cocci, which are spherical; bacilli, which are rod-shaped; and spirilli, which are spiral-shaped.
In practice
Streptococcus forms chains of cocci, and Spirillum volutans shows the true corkscrew spiral; Vibrio cholerae's curved rod shows the three shapes aren't exhaustive.
Where people slip
Shape alone does not sort prokaryotes into Bacteria or Archaea— both domains include cocci, bacilli, and spirilli forms.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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