Vitamins, Harmones and Hemoglobin
|A||Can be enzymically formed from retinoic acid.|
|B||Is transported from the intestine to the liver in chylomicrons.|
|C||Is the light-absorbing portion of rhodopsin.|
|D||Is phosphorylated and dephosphorylated during the visual cycle.|
a. Retinyl esters are incorporated into chylomicrons.
b. Retinoic acid cannot be reduced to retinol. Retinal, the aldehyde form of retinol, is the chromophore for rhodopsin. Retinal is photoisomerized during the visual cycle.
c. Retinoic acid, not retinol, is the most important retinoid.