Biochemistry - Vitamins and Coenzymes - Discussion

Discussion :: Vitamins and Coenzymes - Section 1 (Q.No.16)


An early sign of retinol deficiencies in man is

[A]. night blindness
[B]. keratinization
[C]. xeropthalmia
[D]. none of these

Answer: Option A


No answer description available for this question.

Guest said: (Sep 29, 2014)  
Retinol(hydroxyl) is required for the growth, differentiation and maintenance of epithelial cells. Not for vision. So retinal is the one responsible for night blindness Retinal exit in two forms (trans and cis) when few photons strike to retinal, the trans conformation switches to cis leading active rhodopsin receptor then it actives the G protein transducin do cGMP phosphodiesterase converts cGMP (light) into 5'GMP (inactive) , cGMP decrease and no longer bind to the sodium channel therefore Na+ channel close and Na+ couldn't influx into the cell caused hyper-polarized.

Cell hyper-polarized will not produce glutamate (which stimulates bipolar cell to release GABA inhibit optic nerve) thus GABA NOT secrete then it won't inhibit optic nerve so we can see. Deficiency Retinal will cause night blindness.

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