rhodopsin

noun
rho·​dop·​sin | \ rō-ˈdäp-sən How to pronounce rhodopsin (audio) \

Definition of rhodopsin

: a red photosensitive pigment in the retinal rods of the eye of most vertebrates that is important in vision in dim light

called also visual purple

Examples of rhodopsin in a Sentence

Recent Examples on the Web Some use chlorophyll to convert sunlight during photosynthesis and others use rhodopsins, proteins that bind to a form of vitamin A called retina to capture light. Shandria Sutton, Science | AAAS, "New ‘light-eating’ protein discovered in the Sea of Galilee," 5 July 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'rhodopsin.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of rhodopsin

1878, in the meaning defined above

History and Etymology for rhodopsin

borrowed from German Rhodopsin, from rhod- rhod- + Greek ópsis "appearance, sight, vision" + German -in -in entry 1 — more at optic entry 1

Note: Term introduced by the German physiologist Wilhelm Kühne (1837-1900) and his assistant August Ewald (1849-1924) in "Untersuchungen über den Sehpurpur," Untersuchungen aus dem Physiologischen Institute der Universität Heidelberg, 1. Band (1878), p. 181: "Was den Sehpurpur im Dunkel ändert, pflegt es z. Th. in derselben Weise zu thun, wie das Licht, d.h. erst eine gelbe Materie, dann farblose Substanz hervorzubringen. Der Kürze wegen und um dem Auslande unsere Bezeichnungen zugänglich zu machen, kann man sagen, Rhodopsin werde erst in Xanthopsin, dieses in Leukopsin zersetzt." ("Those things [i.e., reagents] that convert visual purple in darkness in part act in the same manner as light, that is, they first produce a yellow material, then a colorless substance. For the sake of brevity, and in order to make our designations more accessible to foreigners, we can say that rhodopsin is first broken down into xanthopsin ['visual yellow'], and this into leucopsin ['visual white'].") Kühne's selection of the combining element rhod-, usually meaning "red," is somewhat idiosyncratic, given that he is rendering German Sehpurpur ("visual purple") and not Sehrot ("visual red").

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The first known use of rhodopsin was in 1878

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Last Updated

27 Jan 2020

Cite this Entry

“Rhodopsin.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/rhodopsin. Accessed 29 Feb. 2020.

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More Definitions for rhodopsin

rhodopsin

noun
rho·​dop·​sin | \ rō-ˈdäp-sən How to pronounce rhodopsin (audio) \

Medical Definition of rhodopsin

: a red photosensitive pigment in the retinal rods of marine fishes and most higher vertebrates that is important in vision in dim light, is quickly bleached by light to a mixture of opsin and retinal, and is regenerated in the dark

called also visual purple

More from Merriam-Webster on rhodopsin

Britannica.com: Encyclopedia article about rhodopsin

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