Re: Visual Violet (isodopsin)

On Mon, 27 Oct 2003 22:27:33 GMT, "Alan French"
<[EMAIL PROTECTED]> wrote:

>
>"r norman" <[EMAIL PROTECTED]> wrote in message
>news:[EMAIL PROTECTED]
>> On Mon, 27 Oct 2003 02:04:45 GMT, "Alan French"
>> <[EMAIL PROTECTED]> wrote:
>>
>> >My rather aged book on zoology has a brief mention saying the cones in
>the
>> >eye contain visual violet, and adds that little is known about it.  Now I
>> >know visual purple (rhodopsin) increases the eye's sensitivity in dim
>light,
>> >but what does visual violet do?  Same thing in cones?
>> >
>> >Thanks.
>> >
>> >Clear skies, Alan
>>
>> Your book must be rather aged, indeed.  A lot is known about exactly
>> how the rods and cones respond to light.
>>
>> The proper term for the substance is "rhodopsin", also called "visual
>> purple".  Google will give you a lot of sites for rhodopsin.  This one
>> seems to be pretty good:
>
>Thanks for the reply, but I actually was asking about visual violet.  As an
>amateur astronomer I was familiar with visual purple, and had never before
>heard of visual violet.  From the one brief reference I have found since
>noticing it in the book it sound like it may have something to do with
>differentiating between colors in the cones, but the piece was only a brief
>outline.
>
>Clear skies, Alan

It is really the same thing as rhodopsin and works the same way.
Different proteins give the cones different spectral sensitivities.
So yes, indeed, it is part of the color system.  But it is the
photoreceptor, itself, not just an adjunct or  something to increase
the sensitivity or modify the color detection.  It IS the detector.