An isolated strain of sheep was found in New Zealand. Most...

Name: Problem 66, Chapter 4: Biochemistry
Uploaded: 2020-06-16T04:50:52-08:00
Duration: 33 s
Channel: Sam Limsuwannarot
Description: An isolated strain of sheep was found in New Zealand. Most of these sheep carried the gene for predisposition to scrapie, yet none of them ever came down with the disease. How do these facts relate to the transmission of prion diseases?

An isolated strain of sheep was found in New Zealand. Most of these sheep carried the gene for predisposition to scrapie, yet none of them ever came down with the disease. How do these facts relate to the transmission of prion diseases?

Key Concepts

Transmission Mechanisms

Prion disease transmission is unique compared to other infectious diseases because it relies on the physical transfer of misfolded proteins rather than nucleic acids. The lack of disease in a genetically predisposed but isolated population underscores that transmission largely depends on environmental exposure to infectious prions rather than on genetic factors alone.

Exogenous Seeding Requirement

The manifestation of prion diseases typically requires an exogenous trigger—in other words, the introduction of misfolded prion proteins (seeds) into an organism. Even if an organism has a genetic predisposition, the disease may not develop without this initiating misfolded protein, highlighting the importance of both the seed and the host environment in disease propagation.

Prion Diseases

Prion diseases are a group of neurodegenerative disorders caused by misfolded prion proteins that can induce other normally folded proteins to misfold. This process of templated misfolding leads to a buildup of harmful aggregates, ultimately resulting in neurological damage. Importantly, the disease is not caused by a conventional pathogen like a virus or bacteria but by an infectious protein conformation.

Genetic Predisposition

Genetic predisposition refers to the presence of certain alleles that increase an organism’s susceptibility to a disease. In the context of prion diseases, specific variations in the gene coding for the prion protein can make an individual more prone to developing the disease when exposed to misfolded prions, though the gene alone is not sufficient to trigger the disease.

Transcript

Please give Ace some feedback