Mad cow disease is caused by deformed proteins called prions. The disease is spread when meat from an infected cow is eaten. Pri
ons can cause normal proteins to become deformed, producing more prions. After a few years, the brain of an infected person or cow looks like a sponge full of holes. Are prions considered organisms?
Prions, however, are not living organisms. Prions are infectious proteins. For unknown reasons, these proteins refold abnormally and cause a domino effect in surrounding proteins which in turn mutate into stable structures
