Concept
Photopigment
Related concepts (15)
Photoreceptor protein
Photoreceptor proteins are light-sensitive proteins involved in the sensing and response to light in a variety of organisms. Some examples are rhodopsin in the photoreceptor cells of the vertebrate retina, phytochrome in plants, and bacteriorhodopsin and bacteriophytochromes in some bacteria. They mediate light responses as varied as visual perception, phototropism and phototaxis, as well as responses to light-dark cycles such as circadian rhythm and other photoperiodisms including control of flowering times in plants and mating seasons in animals.
Scotopic vision
In the study of human visual perception, scotopic vision (or scotopia) is the vision of the eye under low-light conditions. The term comes from Greek skotos, meaning "darkness", and -opia, meaning "a condition of sight". In the human eye, cone cells are nonfunctional in low visible light. Scotopic vision is produced exclusively through rod cells, which are most sensitive to wavelengths of around 498 nm (blue-green) and are insensitive to wavelengths longer than about 640 nm (red-orange).
Cryptochrome
Cryptochromes (from the Greek κρυπτός χρώμα, "hidden colour") are a class of flavoproteins found in plants and animals that are sensitive to blue light. They are involved in the circadian rhythms and the sensing of magnetic fields in a number of species. The name cryptochrome was proposed as a portmanteau combining the chromatic nature of the photoreceptor, and the cryptogamic organisms on which many blue-light studies were carried out. The genes Cry1 and Cry2 encode the two cryptochrome proteins CRY1 and CRY2, respectively.
Phytochrome
Phytochromes are a class of photoreceptor in plants, bacteria and fungi used to detect light. They are sensitive to light in the red and far-red region of the visible spectrum and can be classed as either Type I, which are activated by far-red light, or Type II that are activated by red light. Recent advances have suggested that phytochromes also act as temperature sensors, as warmer temperatures enhance their de-activation. All of these factors contribute to the plant's ability to germinate.
Melanopsin
Melanopsin is a type of photopigment belonging to a larger family of light-sensitive retinal proteins called opsins and encoded by the gene Opn4. In the mammalian retina, there are two additional categories of opsins, both involved in the formation of visual images: rhodopsin and photopsin (types I, II, and III) in the rod and cone photoreceptor cells, respectively. In humans, melanopsin is found in intrinsically photosensitive retinal ganglion cells (ipRGCs). It is also found in the iris of mice and primates.
Cone cell
Cone cells, or cones, are photoreceptor cells in the retinas of vertebrates' eyes, including the human eye. They respond differently to light of different wavelengths, and the combination of their responses is responsible for color vision. Cones function best in relatively bright light, called the photopic region, as opposed to rod cells, which work better in dim light, or the scotopic region. Cone cells are densely packed in the fovea centralis, a 0.
Photoreceptor cell
A photoreceptor cell is a specialized type of neuroepithelial cell found in the retina that is capable of visual phototransduction. The great biological importance of photoreceptors is that they convert light (visible electromagnetic radiation) into signals that can stimulate biological processes. To be more specific, photoreceptor proteins in the cell absorb photons, triggering a change in the cell's membrane potential. There are currently three known types of photoreceptor cells in mammalian eyes: rods, cones, and intrinsically photosensitive retinal ganglion cells.
Visual perception
Visual perception is the ability to interpret the surrounding environment through photopic vision (daytime vision), color vision, scotopic vision (night vision), and mesopic vision (twilight vision), using light in the visible spectrum reflected by objects in the environment. This is different from visual acuity, which refers to how clearly a person sees (for example "20/20 vision"). A person can have problems with visual perceptual processing even if they have 20/20 vision.
Retinal
Retinal (also known as retinaldehyde) is a polyene chromophore. Retinal, bound to proteins called opsins, is the chemical basis of visual phototransduction, the light-detection stage of visual perception (vision). Some microorganisms use retinal to convert light into metabolic energy. In fact, a recent study suggests most living organisms on our planet ~3 billion years ago used retinal to convert sunlight into energy rather than chlorophyll. Since retinal absorbs mostly green light and transmits purple light, this gave rise to the Purple Earth Hypothesis.
Retinal ganglion cell
A retinal ganglion cell (RGC) is a type of neuron located near the inner surface (the ganglion cell layer) of the retina of the eye. It receives visual information from photoreceptors via two intermediate neuron types: bipolar cells and retina amacrine cells. Retina amacrine cells, particularly narrow field cells, are important for creating functional subunits within the ganglion cell layer and making it so that ganglion cells can observe a small dot moving a small distance.