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Rod cells are photoreceptor cells in the retina of the eye that can function in lower light better than the other type of visual photoreceptor, cone cells. Rods are usually found concentrated at the outer edges of the retina and are used in peripheral vision. On average, there are approximately 92 million rod cells (vs ~6 million cones) in the ...
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.
It is the cone cells, which are used for photopic vision, that facilitate color vision. Each type - or class - of cones is defined by its opsin, a protein fundamental to the visual cycle that tunes the cell to certain wavelengths of light. The opsins present in cone cells are specifically called photopsin. The spectral sensitivities of the ...
The four pigments in a bird's cone cells (in this example, estrildid finches) extend the range of color vision into the ultraviolet. [1]Tetrachromacy (from Greek tetra, meaning "four" and chroma, meaning "color") is the condition of possessing four independent channels for conveying color information, or possessing four types of cone cell in the eye.
Trichromatic color vision is the ability of humans and some other animals to see different colors, mediated by interactions among three types of color-sensing cone cells. The trichromatic color theory began in the 18th century, when Thomas Young proposed that color vision was a result of three different photoreceptor cells .
Rod cells contain the protein rhodopsin and cone cells contain different proteins for each color-range. The process through which these proteins go is quite similar — upon being subjected to electromagnetic radiation of a particular wavelength and intensity, the protein breaks down into two constituent products.
Rhodopsin is a protein found in the outer segment discs of rod cells. It mediates scotopic vision , which is monochromatic vision in dim light. [ 7 ] [ 19 ] Rhodopsin most strongly absorbs green-blue light (~500 nm) [ 20 ] [ 21 ] and appears therefore reddish-purple, hence the archaic term "visual purple".
Generally, the basic morphologies are spheres (coccus) and round-ended cylinders or rod shaped (bacillus). But, there are also other morphologies such as helically twisted cylinders (example Spirochetes), cylinders curved in one plane (selenomonads) and unusual morphologies (the square, flat box-shaped cells of the Archaean genus Haloquadratum ...
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