11-cis-retinal

Definition

11-cis-retinal is a vital chromophore involved in the phototransduction process of vision, serving as the light-absorbing molecule in the visual cycle. It is a derivative of vitamin A and exists in a specific isomeric form that is crucial for its function in converting light into electrical signals in the retina. When it absorbs photons, 11-cis-retinal undergoes isomerization to all-trans-retinal, triggering a cascade of biochemical reactions that ultimately lead to visual perception.

5 Must Know Facts For Your Next Test

1. 11-cis-retinal is crucial for the functioning of rod cells, allowing them to detect low levels of light, which is essential for night vision.
2. The isomerization of 11-cis-retinal to all-trans-retinal leads to a conformational change in rhodopsin, activating a G-protein signaling pathway.
3. After the light-induced reaction, all-trans-retinal must be converted back to 11-cis-retinal through a series of enzymatic steps in the visual cycle to ensure continuous vision.
4. Deficiency in 11-cis-retinal can lead to vision problems such as night blindness due to impaired phototransduction.
5. Isomerization of 11-cis-retinal occurs on a time scale of picoseconds, highlighting its rapid response to light stimuli.

Review Questions

• How does the structure of 11-cis-retinal influence its function in vision?
  • The unique structure of 11-cis-retinal, with its specific configuration, allows it to effectively absorb photons and undergo isomerization when exposed to light. This structural property is essential for its role as a chromophore in rhodopsin, where it facilitates the conversion of light into electrical signals. Any alteration in this structure could hinder its ability to trigger the phototransduction cascade, resulting in impaired vision.
• Discuss the significance of the visual cycle in relation to the role of 11-cis-retinal in maintaining vision.
  • The visual cycle is crucial for regenerating 11-cis-retinal after it has been converted to all-trans-retinal during light exposure. This cycle ensures that sufficient amounts of 11-cis-retinal are available for continuous visual signaling. Without this regeneration process, photoreceptors would quickly become depleted of their chromophore, leading to diminished vision and potential blindness under low-light conditions.
• Evaluate the consequences of a deficiency in 11-cis-retinal on overall visual function and discuss potential treatments.
  • A deficiency in 11-cis-retinal severely impacts visual function, leading to conditions such as night blindness due to disrupted phototransduction. The inability to convert light into electrical signals results from insufficient availability of this critical chromophore. Potential treatments may include supplementation with vitamin A or other compounds that promote the regeneration of 11-cis-retinal, thereby restoring proper function in photoreceptor cells and improving overall vision.

Related terms

Rhodopsin: A light-sensitive receptor protein found in the photoreceptor cells of the retina that contains 11-cis-retinal as its chromophore.

Phototransduction: The biochemical process by which light is converted into electrical signals in the retina, involving various proteins and retinal isomers.

Visual Cycle: The series of biochemical reactions that regenerate 11-cis-retinal from all-trans-retinal after it has been used in the phototransduction process.