Question

What is a prion? Explain how a prion relies on normal cellular proteins to cause a disease such as mad cow disease.

Short answer

Prions are pathogenic agents that can cause disease. They are able to replicate themselves although they do not contain any genetic material. Prions convert normal brain proteins into the disease-causing form. In the case of mad cow disease, the prions convert the normal brain proteins into the prion form, leading to a build-up of abnormal proteins which form clumps and result in neural damage. The mad cow disease can be transmitted to humans through consumption of infected meat.

Step-by-step solution

Understanding Prions

Prions are abnormal, pathogenic agents that can cause disease. They are able to replicate themselves although they do not contain any genetic material. Prions are actually incorrect forms of normal brain proteins, denoted as PrP^C, which when folded incorrectly change into a disease-causing form known as PrP^Sc.

Function of Prions

Prions would typically enter an organism through ingestion. Upon entering an organism, prions bind to normal protein molecules and convert them into the form of the prion, thereby replicating themselves.

Prions and Mad Cow Disease

In the case of mad cow disease, also known as Bovine Spongiform Encephalopathy (BSE), the prions convert the normal brain proteins into the prion form. This leads to a build-up of abnormal proteins in the brain which form clumps and cause neural damage, leading to characteristic symptoms. This disease is transmissible to humans through the consumption of infected meat and can lead to a similar condition in humans called new variant Creutzfeld-Jacob disease (vCJD).