Talk:Retinal

message: I'm trying to write about opsins, and I can't decide what the word should mean. The usage in the scientific literature is inconsistent. I can't find a pattern. It's giving me fits. The article will need a a usage section.
J G Campbell (talk) 14:16, 11 March 2009 (UTC)
thread_title:  Usage of opsin 

message: Retinal also means "of, or pertaining to, the retina" – Can this be made into a disambiguation page? Morganfitzp 15:01, 8 May 2006 (UTC)
replies: text: Not a good idea; it would be like making a disambig on neural, which can mean "of, or pertaining to, the neuron".  Anyway, I just started the retinal article, feel free to contribute. --Sadi Carnot 14:53, 16 September 2006 (UTC)
thread_title:  Retinal can be confused with retinal 

message: The symbol in your figure and caption looks like a "gamma" to me.  In chemistry, "light" (UV to visible to IR) is frequently indicated by "h nu" (Planck's constant h, Greek nu).  Or sometimes a squiggly thunderbolt symbol, if you have one.  I'm not sure what gamma symbolizes except maybe gamma radiation.  Gamma rays are used to induce some reactions, e.g., reactions in crystals.  
This is a "gamma": γ .  This is a "nu": ν .  Let there be light, hν , over your arrow and in your caption. —The preceding unsigned comment was added by 129.64.51.50 (talk) 20:51, 6 December 2006 (UTC)
replies: text: Whilst γ is used to represent gamma rays in the context of nuclear reactions, γ and hν may be used interchangeably to represent a photon of any energy. Eutactic (talk) 12:25, 18 February 2009 (UTC)
thread_title:  "Light" Symbol in Figure 

message: Hi.Perhaps Conjugated system would be more appropriate than unsaturated.Dogchaser 09:23, 19 February 2007 (UTC)
thread_title:  Conjugated instead of unsaturated 

message: I’m not sure how to fit this theory in. See:
* 
* 
* 
—LOL 00:11, 16 April 2007 (UTC)
replies: text: The use of retinal by archaea is worth mentioning, if it isn't mentioned already.  The Purple Earth hypothesis is far too far removed from the retinal molecule to be included in the same article.  If a Purple Earth article is created (and I may if I get time) it would link here when mentioning retinal. Robert Brockway 07:23, 8 May 2007 (UTC)
thread_title:  Purple Earth 

message: In the overview section, "...the retinal molecule absorbs a photon into one of the pi bonds found between the eleventh and twelfth carbon atoms..." sounds bizarre.  As far as I know, photons generally interact with an entire molecule and not with single bonds, even if the only change is seen in a single bond.  Would it perhaps be more accurate to say something like "The incident photon induces a state change in a retinal molecule, causing the pi bond between carbons 11 and 12 to change conformation"?  I don't think that really changes the accessibility of the article but avoids technical errors JaredAllred (talk) 17:34, 13 January 2008 (UTC)
thread_title:  Photon Absorption 

message: Seems remiss not to include any mention of dehydroretinal, which in many vertebrate species (e.g. amphibians) is used as the chromophore instead of retinal for at least part of the animal's development.  Not the greatest reference, but its a start...  --Chinasaur (talk) 14:46, 4 February 2009 (UTC)
replies: text: I've put dehydroretinal in the chembox under related compounds. It's on my agenda. J G Campbell (talk) 22:38, 9 March 2009 (UTC)
thread_title:  Dehydroretinal 

message: I'm taking out this sentence: "It takes a minimum of five photons to trigger a nerve impulse", which cites Feynman's QED.  This is wrong; you must have misinterpreted Feynman.  See, for example: 
S. Hecht, S. Shlaer, and M. H. Pirenne. Energy, quanta, and vision. The Journal of General Physiology, 25(6):819–840, 1942.
D. A. Baylor, T. D. Lamb, and K.-W. Yau. Responses of retinal rods to single photons. J Physiol, 288:613–634, March 1979.
H. B. Barlow, W. R. Levick, and M. Yoon. Responses to single quanta of light in retinal ganglion cells of the cat. Vision Res, Suppl 3:87–101, 1971.
--Chinasaur (talk) 14:53, 4 February 2009 (UTC)
replies: text: You're both right. Certainly, a single photon can photoisomerize the chromophore, and trigger a cascade; but about four of five photons entering the human eye under the best dark-adapted conditions go astray. The abstract of the cat reference supports this. Cats have tapeta lucida which make their eyes almost twice as efficient as human eyes in dim light. Almost two times almost three is about five. J G Campbell (talk) 17:04, 15 March 2009 (UTC)
thread_title:  Number of photons needed 

message: "Heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) respond to a variety of different external stimuli ..."—Palczewski, et al.
Kinky. J G Campbell (talk) 19:55, 14 March 2009 (UTC)
thread_title:  GPCRs are sexy 

message: Before the biochemistry of vision was understood, chemicals were tested to see if they were a vitamin A in animals. Any chemical that restored vision was a "vitamin A". But what makes a chemical a vitamin A  is that it can be converted to retinal by the animal. In the animal tests retinal obviously would perform as a vitamin A would. But it is really the visual photon receptor molecule and only secondarily it own vitamin. Nick Beeson (talk) 14:48, 28 November 2020 (UTC)
thread_title:  vitamin A