Final answer:
Both antibody-antigen binding and normal prion protein conversion into pathogenic prions involve conformational changes of proteins, where antibodies undergo structural changes for immune response and PrPC misfolds into PrPSc, leading to neurodegenerative diseases like CJD and mad cow disease.
Step-by-step explanation:
When an antibody binds to an antigen and when a normal prion protein (PrPC) is converted into a pathogenic prion, both processes involve a conformational change of proteins. Antibodies undergo a structural change to tightly bind to antigens, crucial for the immune response. In the case of prion diseases, normal cellular prion protein (PrPC) is transformed into the infectious form (PrPSc) by misfolding. This misfolded prion can then induce other normal prion proteins to become misfolded, resulting in a chain reaction that leads to the accumulation of PrPSc proteins, forming plaques and causing neurodegenerative diseases like Creutzfeldt-Jakob disease (CJD) and Bovine Spongiform Encephalopathy (BSE), also known as mad cow disease. These diseases are characterized by rapid degeneration of brain tissue giving it a characteristic spongy texture due to vacuole formation.