Transduction of light in the retina
(i) Photo-transduction is the process in which light is converted into electric signal in rods and cone cells of the retina.
(ii) Both rod and cone cells contain a photopigment Rhodopsin.
(iii) Rhodopsin contains retinal (aldehyde of vitamin A) a light sensitive molecule covalently linked to a protein called opsin.
(iv) When struck by light retinal (in cis form) isomerizes to a trans- form.
(v) Isomerization of retinal activates rhodopsin to start a cascade of events leading to firing of an impulses to the brain.
(vi) After depolarization, transform of retinal is converted back to the cis form to be reused using ATP energy.
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Dr. Bbosa Science
