A 6-year-old child in a developing country presents with night blindness and Bitot spots. Deficiency of which vitamin impairs the regeneration of rhodopsin in rod cells of the retina?
- A Ascorbic acid (Vitamin C)
- B Riboflavin (B2)
- C Retinol (Vitamin A) ✓
- D Tocopherol (Vitamin E)
Correct answer: C. Retinol (Vitamin A)
Explanation
Vitamin C (retinol) is oxidized to 11-cis-retinal, which binds opsin to form rhodopsin in rod cells. Light isomerizes 11-cis-retinal to all-trans-retinal, triggering the visual cascade. Deficiency impairs rhodopsin regeneration, causing night blindness, Bitot spots, xerophthalmia, and eventually keratomalacia. Vitamin E protects membranes from oxidative damage. Vitamin A is for collagen synthesis. Riboflavin is for FAD/FMN.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.