In this video, we're going to introduce prions. And so the term prions is actually derived from proteinaceous infectious agents. And you can see that with the bolded terms here to help create that word, prions. And so by proteinaceous, what this is referring to is that these infectious agents are made of proteins and only proteins. And these prions, like viruses and viroids, are obligate intracellular parasites, which once again just means that they must infect a living cell and get inside of the cell in order to replicate themselves. And so, unlike viruses and viroids, these prions, once again, are made of only misfolded proteins. So they only consist of proteins and that's why they are proteinaceous. And, you can see that with the prions here. Now prions, again, they are misfolded proteins themselves. However, these misfolded prion proteins can cause normal proteins to misfold. And ultimately, a misfolded protein is going to lose its function, and that can cause disease. And so prions are linked to several slow degenerative diseases such as scrapie and mad cow disease.
And so if we take a look at our image down below over here on the left-hand side, notice that we're showing you the structure of a normal protein. And over here on the right, what we're showing you is the structure of the prion, which is going to be a misfolded protein itself. And so notice that the shape of this prion is different than the shape of the normal protein. And so over here on the right-hand side, we're showing you the brain of a healthy individual that's going to have normal proteins. However, if this individual is infected with a prion, then the prion can cause normal proteins to transform into prions. And so you can see that those normal proteins have transformed into prions, misfolded proteins that have lost their function, and that can lead to diseases. And so this represents the diseased brain.
And so this here concludes our brief introduction to prions, and once again, we'll be able to talk more about prions later in our course. But for now, I'll see you all in our next video.
