Other Acellular Entities: Prions and Viroids

Free Response

Prions are responsible for variant Creutzfeldt-Jakob Disease, which has resulted in over 100 human deaths in Great Britain during the last 10 years. How do humans contract this disease?


This prion-based disease is transmitted through human consumption of infected meat.

How are viroids like viruses?


They both replicate in a cell, and they both contain nucleic acid.

A botanist notices that a tomato plant looks diseased. How could the botanist confirm that the agent causing disease is a viroid, and not a virus?


The botanist would need to isolate any foreign nucleic acids from infected plant cells, and confirm that an RNA molecule is the etiological agent of disease. The botanist would then need to demonstrate that the RNA can infect plant cells without a capsid, and that the RNA replicates, but is not translated to produce proteins.