Question

Arrange the events that occur after a rod cell absorbs light according to the order in which they occur, with the earliest event at the top:

Answer 1

After light absorption by a rod cell, a photon initiates the isomerization of retinal, activating rhodopsin, which in turn activates a G protein that hyperpolarizes the cell and decreases neurotransmitter release, leading to visual perception.

Step-by-step explanation:

Steps of Light Absorption in Rod Cells

1. A photon of light strikes the retinal molecule in a rod cell, causing a shape change from the cis to trans isomer.
2. This isomerization activates the photopigment rhodopsin.
3. Activated rhodopsin triggers a G protein, which leads to changes in membrane potential.
4. Change in membrane potential results in the closure of Na+ channels, hyperpolarizing the cell and decreasing neurotransmitter release.
5. The photoreceptor sends a signal through the retinal ganglion cells (RGCs), which eventually leads to visual perception.

Upon light absorption by the rod cells in the retina, a series of events lead to visual transduction. The process begins when light initiates a change in shape of the retinal molecule in the photoreceptors, activating rhodopsin. Then, an activated G protein changes the membrane potential of the photoreceptor, resulting in reduced neurotransmitter release and hyperpolarization of the cell. This process is crucial for the conversion of light energy into a neural signal.