Transcript Document
Beyond Viruses…Beyond Viroids… Can create an “infection” that can lead to the death of the “infected organism? …appears to be able to replicate itself… …is not a bacteria! …is smaller than a virus? …is not a virus! …contains no genetic information …whose structure is made by all living things… PRIONS: The Brain Eater… A PRION is a… PROteinaceous INfectious particle. This simply means that a protein can cause a particular disease and it can be given to another individual and they can then get the same disease. PRIONS: DID YOU KNOW… •People often assume that scientists try to prove hypotheses or theories. •WRONG •Hypotheses can never be proved; they can only be disproved. •A hypothesis that fails one or more tests is considered disproved and it is discarded. •A valid hypothesis can be revised. PRIONS: The Brain Eater… In Class Reading… The History of Scrapie, CDJ and Kuru PRIONS: Are PRIONs a new form of life? 1- Are PRIONs made of cell? NO 2- Are PRIONs organized? YES 3- Do PRIONs use energy? NO 4- Are PRIONs responsive? NO (hypothesized) PRIONS: Are PRIONs a new form of life? 5- Do PRIONs grow? (enlarge and divide) NO 6- Do PRIONs reproduce? YES (hypothesized) ~kind of, they recruit normal proteins by changing their shape 7- Do PRIONs adapt? Don’t know yet, they may mutate in other viable forms however. PRIONS: Are PRIONs a new form of life? 8- Do PRIONs die? NO, however like all proteins, their structure can be degraded or denatured by heat. 9- Do PRIONs come from pre-existing prions? YES (hypothesized) ~ existing PRIONs convert normal Prion-like protein structures into abnormal viable PRION geometries. PRIONS: Origin & Structure Pre-infectious prion proteins or PrPc, like this one are naturally created by and are found in the membranes of normal host cells. PRIONS: Origin & Structure All mammals appear to have prion protein genes and the gene sequences are similar, but not identical, in related species. PRIONS: Transformations PRIONS: Transformations PRIONS: Infection O – Origin of PRIONs Contaminated meat Digestive Track Blood Stream L – White Blood Cell S – Spleen N – Spleen to Brain B – Brain Rouge Infectious PRIONS: Transformation PRION > Nerve Cell Normal Prion Protein Rouge PRION Transforms Normal Prion PRIONS: Shape Transformation Normal Prions Infectious PRIONS PRIONS: Shape Transformation Normal Prions Infectious PRIONS PRIONS: What is the evidence? Normal Brain Tissue “Dead Space” Amyloid Clusters Diseased Brain Tissue PRIONS: What is the Impact? One part of the prion protein can cause apoptosis, or programmed cell death; …perhaps this mechanism explains the pattern of the disease. PRIONS: What is the Impact? Prions induce no immune reactions within the human. …perhaps this mechanism explains the pattern of the disease.