Consider visual transduction in rod photoreceptors in the vertebrate retina. Which of the following steps does NOT normally amplify the signal in this pathway?
A) Activation of transducin by active rhodopsin
B) Blockage of Na⁺ influx by cation-channel closure
C) Cation-channel closure due to cGMP depletion
D) Depletion of cGMP by active cGMP phosphodiesterase
E) All of the above DO involve amplification

Question

Quizplus · Accepted Answer

A single quantum of light can result in the hydrolysis of more than 10⁵ cyclic GMP molecules in the visual transduction cascade. This closes only a few hundred cyclic-GMP-sensitive channels.

Consider Visual Transduction in Rod Photoreceptors in the Vertebrate Retina