Question

In terms of light being present or not, when is the Phototransduction cascade triggered?

a) In the presence of light
b) In the absence of light

Answer 1

The phototransduction cascade is triggered in the presence of light when it causes a change in the shape of the retinal in photoreceptor cells, leading to a series of events that convert light into a neural signal. The correct option is a).

Step-by-step explanation:

Phototransduction Cascade Triggering

The phototransduction cascade is triggered in the presence of light. When light strikes photoreceptor cells in the retina, such as rods and cones, it initiates a change in the shape of a light-absorbing molecule called retinal. This alteration from a bent (cis) form to a linear (trans) form activates a photopigment called rhodopsin.

The activation of rhodopsin leads to a sequence of biochemical events that ultimately result in the hyperpolarization of the photoreceptor cell, effectively converting the light signal into a neural signal that the brain can process.

During this cascade, various proteins and enzymes are involved, including a G-protein called transducin. This process is essential for vision, allowing organisms, including humans, to detect light and convert it into a form that can be interpreted by the nervous system as visual information. Option a) is the correct one.