Linear chains of amino acids that singly or in multiples of two or more form into proteins. Chains of just two amino acids are called, chains of three are, and any more are polypeptides.inear chains of amino acids that singly or in multiples of two or more form into proteins. Chains of just two amino acids are called, chains of three are, and any more are polypeptides.
Vitiligo: A Common Cause of Loss of Skin Pigment. Melanin is the pigment that gives the skin its characteristic color. Vitiligo is caused by a loss of pigment in the skin, due to destruction of pigment-forming cells known as melanocytes. Although vitiligo affects all races equally, it is more noticeable in dark-skinned people. Vitiligo can cause cosmetic problems.
Normally, the color of hair and skin is determined by melanin. Vitiligo occurs when the cells that produce melanin die or stop functioning. Vitiligo affects people of all skin types, but it may be more noticeable in people with darker skin. The condition is not life-threatening or contagious. It can be stressful or make you feel bad about yourself.