Four Capsid Shape Classes
This video presents the same text shown beside it, spoken and on screen. It adds nothing the text does not say.
State
Viral capsids fall into four shape classes: helical, icosahedral, enveloped, and head-and-tail, built from repeating protein subunits called capsomeres.
Show
Tobacco mosaic virus is helical, poliovirus is icosahedral, and bacteriophage T4 combines an icosahedral head with a helical tail.
Watch for
Capsid shape alone predicts neither a virus's disease nor its host species— it only helps sort viruses into families.