The proteins alter other normal proteins within the living cells are termed as

Step-by-step solution

Viruses, Viroids and Prions are acellular organisms and hence did not find a place in famous Whittaker's Five - Kingdom classification. Viruses did not have organelles and hence no metabolism and also requires a host for its survival. Prions are also acellular and consist of just protein structure folded variously. These proteins can alter normal proteins in the brain and can cause various neurological infections like BSE (Bovine spongiosum encephalopathy) also known as Mad- cow disease and CJD (Cr. Jacob disease).