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photoreceptor a cell or a subtance?

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photoreceptor a cell or a subtance?

Postby ffixcth » Fri Mar 04, 2005 2:20 pm

Can anyone tell me that is photoreceptor is a type of cell that sensitive to light or is photoreceptor a substance in the retina cell that is sensitive to light?
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Postby RobJim » Sat Mar 05, 2005 1:51 pm

Your grammar is poor and because of this it's hard to understand what you want to know.

According to dictionary.reference.com, a photoreceptor is

A nerve ending, cell, or group of cells specialized to sense or receive light.

If you look at the word, you can see that it should be anything that receives light in some way. A solar panel for solar energy generation would be a photoreceptor too.
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Postby MrMistery » Sun Mar 06, 2005 10:22 pm

The fotoreceptor is not necessarily a cell: the first fotoreceptor in the living world appears at Euglena virdis and it is an organelle. I do not know how to translate it's name(in romanian it is "stigma"). However, it moves the scourge to where the light is
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Postby MrMistery » Sun Mar 06, 2005 10:25 pm

by the way, who knows how plants detect light?
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Postby thank.darwin » Sun Mar 06, 2005 10:36 pm

What do you mean detect light - :?:
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Postby biostudent84 » Mon Mar 07, 2005 7:14 pm

RobJim wrote:Your grammar is poor and because of this it's hard to understand what you want to know


For the record, I think it's pretty good for someone from Singapore...

A photoreceptor, by definition, is a nerve bundle designed to detect the presence of light. They are connected to the Rod and Cone cells located on the back of the retina. For example, in the cones, when an orange light strikes the cell, the orange pigment dissolves. The photoreceptor bundle sends a message to the brain that says "Hey! Look! Orange!"

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Postby MrMistery » Mon Mar 07, 2005 8:07 pm

By detecting light, I mean how do they know when it is there :)
For example, the dandelion flower opens when it is light and closes when it's dark. How does the plant know when it is light or dark?
By the way, I didn't see the question was adressed to the retina. It's deffinetly a cell, as everyone said
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Postby biostudent84 » Mon Mar 07, 2005 8:26 pm

MrMistery wrote:By detecting light, I mean how do they know when it is there :)
For example, the dandelion flower opens when it is light and closes when it's dark. How does the plant know when it is light or dark?


Correct me if I'm wrong, but I think there's a pathway to detect rate of photosynthesis. I'm fairly sure that this mechanism opens the petals when the rate of photosynthesis is high enough. I.E. When the sun is up.
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Postby MrMistery » Tue Mar 08, 2005 8:52 pm

Since I have absolutely no idea, I guess you must be right
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