When a ligand attaches to a receptor, which of the following occurs first? (Consider a ligand to be a hormone or a cell messenge
r) A) There is a change in shape of the ligand which causes the signaling cascade
B) There is a change in shape of the receptor which triggers the stopping of the signaling cascade
C) There is a change in shape of the receptor which triggers the beginning of the signaling cascade
D) There is a change in shape of the receptor which causes the ligand to be released
Prions, however, are not living organisms. Prions are infectious proteins. For unknown reasons, these proteins refold abnormally and cause a domino effect in surrounding proteins which in turn mutate into stable structures
