A genetic form of "night blindness" (i.e. poor vision in dim light) is caused by mutations in genes encoding rhodopsin kinase (RK) and arrestin. The mutations reduce the dynamic range of light perception, and the affected individuals have a prolonged light response and adapt very slowly to low light (when entering a dark theater room, for example). Which of the following mutations do you expect to be the cause?
A) Loss-of-function RK mutations and loss-of-function arrestin mutations
B) Loss-of-function RK mutations and gain-of-function arrestin mutations
C) Gain-of-function RK mutations and loss-of-function arrestin mutations
D) Gain-of-function RK mutations and gain-of-function arrestin mutations

Question

Quizplus · Accepted Answer

Mice or humans with defects in RK, or its downstream regulator arrestin, have a prolonged light response, incapable of adapting quickly to sudden drops in ambient light intensity.

A Genetic Form of "Night Blindness" (I