photoreceptor

Examples of photoreceptor in the following topics:

• Plant Responses to Light

  • The response of plants to light is mediated by different photoreceptors: a protein covalently-bonded to a light-absorbing pigment called a chromophore; together, called a chromoprotein.
  • The chromophore of the photoreceptor absorbs light of specific wavelengths, causing structural changes in the photoreceptor protein.
  • Sensory photoreceptors absorb light in these particular regions of the visible light spectrum because of the quality of light available in the daylight spectrum.

• Transduction of Light

  • When light hits a photoreceptor, it causes a shape change in the retinal, altering its structure from a bent (cis) form of the molecule to its linear (trans) isomer.
  • Photoreceptors in the retina continuously undergo tonic activity.
  • Sometimes horizontal cells carry signals from one rod or cone to other photoreceptors and to several bipolar cells.
  • When a rod or cone stimulates a horizontal cell, the horizontal cell inhibits more-distant photoreceptors and bipolar cells, creating lateral inhibition.
  • (a) Rhodopsin, the photoreceptor in vertebrates, has two parts: the trans-membrane protein opsin and retinal.

• Blue Light Response

  • Like all plant photoreceptors, phototropins consist of a protein portion and a light-absorbing portion, called the chromophore, which senses blue wavelengths of light.
  • Cryptochromes are another class of blue-light absorbing photoreceptors.

• Anatomy of the Eye

  • There are two types of photoreceptors in the retina: rods and cones.
  • Rods and cones are photoreceptors in the retina.

• Contractile Vacuoles in Microorganisms

  • Structure of Euglena: 1 - Flagellum; 2 - Eye spot / Pigment spot / Stigma; 3 - Photoreceptor; 4 - Short second flagellum; 5 - Reservoir; 6 - Basal body; 7 - Contractile vacuole; 8 - Paramylon granule; 9 - Chloroplasts; 10 - Nucleus; 11 - Nucleolus; 12 - Pellicle

• Neurons

  • An example of a bipolar neuron is a retinal bipolar cell, which receives signals from photoreceptor cells that are sensitive to light and transmits these signals to ganglion cells that carry the signal to the brain.