C.5.3

=Describe the structures and major functions of retinol (vitamin A), calciferol (vitamin D) and ascorbic acid (vitamin C).=

Vitamin A Group
__Structure__ - non polar, fat soluble (see figure below) __Function__ - immunity from disease: growth and development of white blood cells, embryonic development, such as formation of heart, eyes and ears, an antioxidant which help to protect free radicals from damaging cells in the body. __Deficiency__ - can lead to a malfunction in the retina which can lead to night blindness, [|xerophthalmia] (tear glands cease to function), and degeneration of the mucous membranes. __Members of the group__ - retinal has a carboxylic acid functional group and retinol has an alcohol functional group.



Figure 1. Structure of Vitamin A

Vitamin D or calciferol
__Structure__ - non polar, fat soluble vitamin. Occurs in several forms; the most common form is D2 or calciferol (produced by ultraviolet radiation). __Function__ - Absorption of calcium and phosphorus in the intestines from food, maintaining normal levels of calcium in the blood, aids in the formation of strong bones and teeth, needed for the production of a hormone involved in the metabolism of calcium, influence the process of bone mineralization. __Deficiency__ - softening of the bones and low calcium blood level known as: rickets in children and osteomalacia in adults.

Structure of Vitamin D found in the IB Chemistry Data Booklet

Vitamin C or ascorbic acid
__Structure__ - polar water soluble __Function__ - helps form collagen (the protein that gives skin it elasticity) and connective tissue, acts as an antioxidant, strengthens blood vessels, bones, tendons, and ligament tissue. __Deficiency__ - scurvy, where the connective tissues break down. Symptoms of scurvy include muscle weakness, swollen and bleeding gums, loss of teeth, bleeding under the skin, tiredness, and depression. Figure 2. Straight chain structure of Vitamin C (left) and ring chain (right)