Final answer:
Prions are proteinaceous infectious particles that do not contain DNA or RNA. They cause diseases by converting normal proteins into misfolded, disease-causing forms. Prions are associated with progressive brain disorders like mad cow disease and Creutzfeldt-Jakob disease.
Step-by-step explanation:
Prions are proteinaceous infectious particles that can cause diseases. Unlike other infectious agents, prions do not contain DNA or RNA. They are composed entirely of proteins and replicate by converting their normal, healthy counterparts into misfolded, disease-causing forms. Prions are known to contribute to progressive brain disorders such as mad cow disease and Creutzfeldt-Jakob disease.