Rods and Cones (1 Viewer)

[kimmeh]

Is it correct to say that there are three types of iodopsins in cones? or is "iodopsin" just a collective term for it?

 

[kimmeh]

I've read this somewhere:

when light hits the rhodopsin, it absorbs it and spilts it into two parts: retinal and opsin.

it doesnt sound right. someone explain please?

 

[jesshika]

Im getting confused now........

Whats the diffreence between
.Opsin
.Iodopsin
.Scotopsin

Correct me if im wrong, but is Rhodopsin the photo pigment for the Rod and for Cones it is the Photopsin?
Are there any strucutural differences ebtween the two when they both have a retinal bonded with a opsin?
i'm confused !

 

[kimmeh]

opsin is a protein that is found in rhodopsin

iodopsin is in cones and there are thre types, one for a different colour

scotopsin ive never heard of...

umm i learnt that
rhodopsin : in rods
iodopsin/photopsins: cones

now you're confusing me =s

 

[iambored]

found this in a text: ( Mader, S. (2003). Inquiry Into Life. McGraw Hill:Sydney)

"the visual pigments in rods is a deep purple pigment called rhodopsin. rhodopsin is a complex molecule made up of the protein opson and a light-absorbing molecule called retinal, which is a derivative of vitamin A. when a rod absorbs light, rhodopsin splits into opsin and retinal, leading to a cascade of reactions and the closure of the ion channels in the rod cell's plasma membranes.".. etc.

"the cones...colour vision depends on 3 different types of cones, which contain pigments called the B (blue), G (green) and R (red) pigments. each pigment is amde up of retinal and opsin, but which there is a slight differece in the opsin structure of each, which accounts for their individual absorption patterns." (doesn't mention iodopsin though)

 

[kow_dude]

I've read this somewhere:

when light hits the rhodopsin, it absorbs it and spilts it into two parts: retinal and opsin.

it doesnt sound right. someone explain please?

When light strikes rhodopsin, the retinal part becomes 'activated'. This causes rhodopsin to split into its opsin part and a free retinal part. A series of biochemical steps that follows, whereby the activated pigment causes a change in electrical charges of the membrane of the cone (an action potential). This stimulates a bipolar cell generating an impulse in this cell. It then transmits the electrochemical signal to ganglion cells then to the brain.

This is an extract from the communication book by Chidrawi and Mercer... it makes sense =)