Regarding prion protein which of the following statment is true-
Correct Answer: It catalyses abnormal folding of other proteins
Description: Ans. is 'b' i.e., It catalyses abnormal folding of other proteins Prions are infectious proteins that cause degeneration of the central nervous system Q.They are infectious particles that lack nucleic acid Q.Prions are composed largely, if not entirely of PrP molecules Q.Four important points about prions are: -Prions are the only known infectious vatho2ens that are devoid of nucleic acid all other infectious agents possess genomes composed of either RNA or DNA that direct the synthesis of their presence.Prions disease may manifest as infectious, genetic and sporadic disorders; no other group of illness with a single etiology presents with such a wide spectrum of clinical manifestations.Prions disease result from the accumulation of PrP1 the conformation of which differs substantially from that of its precursor. PrP can exist in a variety of different conformations each of which seems to specify a particular disease phenotype.Prion disease: -Prion are fatal neurodegenerative disease caused by transmissible proteins and are characterized by spongiform changes, astrocytic gliomas and neuronal loss from the deposition of insoluble protein aggregates in neural cells.Prions are caused by human prion related protein (PrP) {a glycoprotein rich in a helix).PrP is endogenous to the host and in most people, the PrP protein folds normally leaving the person healthy.Rarely, a mutation in the PrP gene will allow the protein to be made incorrectly and it will fold incorrectly making a PrPsc prion. (Which is a glycoprotein rich in b sheets).These PrPsc prions when exposed to PrP, which is in the process of folding will encourage that PrP to fold incorrectly too, thus creating another PrPsc.While PrP can be processed and cleaned out of a cell once it has been used, PrPsc is shaped differently enough so that it can't be cleaned out and it aggregates inside the cell. These PrPsc aggregates quickly builds up into plaques destroying the nervous tissue.Thus a pathological prion protein serves as the templates for the conformational transformation of normal PrP into PrPsc.Remember PrP - made up of a helix? PrPsc - Made up of b sheet QPathogenesis of Prion's diseaseNormal endogenous human protein (human prion related protein)(PrP)|It is a glycoprotein rich in a helix and it folds normally|Mutation in the PrP protein|Folds improperly and result in PrPsc protein {It is a glycoprotein rich in b sheets)|PrPsc comes in contact with PrP|PrP too will fold incorrectly resulting in more PrPsc|Aggregation of PrPsc|Destruction of nervous tissue Prion disease
Category:
Microbiology
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