Protoplasm was part of a cell.
The process used by the Chameleons to assume the identities of humans involved the use of armband-like devices placed on both subjects. If an armband was removed from the original, the Chameleon that assumed their identity would be killed, reduced to a small blob of protoplasm. (TV: The Faceless Ones)
Because computers were unable to withstand the reality-changing stress, TARDISes required morphologically unstable living organic matter, or protoplasm, for their Block Transfer Computations. (PROSE: Cat's Cradle: Witch Mark)