Dictionary > Amelanism

Amelanism

Definition
noun
A condition characterized by the complete lack of pigments (or melanin)
Supplement
Melanin is a compound that is responsible for the color of the skin, hair, feathers, scales, etc. It is produced in plants, animals, and protists. It is produced within the specialized cells called melanocytes, particularly in specialized organelles called melanosomes. Melanin is derived from the amino acid tyrosine and the production of melanin is referred to as melanogenesis. Melanin is produced by catalyzing tyrosine through the enzyme, tyrosinase. It is important in living organisms since it renders protection against the adverse effects of light exposure. It is capable of absorbing the sun’s UV rays. This is important because without melanin, the sun’s UV rays may damage DNA especially when exposed to sunlight for a longer period. The complete absence of pigmentation due to lack of melanin production is termed amelanism. Hypomelanism is a condition where there is only a partial lack of pigmentation. In contrast, an accentuated pigment production characterizes hypermelanism. Amelanism occurs in animals like in fish, amphibians, reptiles, birds, and mammals. Despite the lack in melanin pigments, animals with amelanism can still have red or yellow spots due to chromatophores that produce non-melanin pigments. It can also occur in humans as albinism (particularly the oculocutaneous type).
Word origin: a- (absence) + melanism
Synonym(s):

  • amelanosis

See also:

  • melanin
  • pigment
  • albino
  • hypomelanism


    You will also like...

    Neural Control Mechanisms
    Neural Control Mechanisms

    Neurons generate electric signals that they pass along to the other neurons or target tissues. In this tutorial, you wil..

    squirrel
    Animal Water Regulation

    Animals adapt to their environment in aspects of anatomy, physiology, and behavior. This tutorial will help you understa..

    Freshwater lake ecosystem
    Freshwater Producers and Consumers

    Freshwater ecosystem is comprised of four major constituents, namely elements and compounds, plants, consumers, and deco..

    Freshwater aquatic plankton
    Freshwater Communities & Plankton

    Planktons are microscopic organisms that live suspended in aquatic habitats. There are two groups: the phytoplanktons an..

    Adaptation Tutorial
    Adaptation Tutorial

    Adaptation, in biology and ecology, refers to the process or trait through which organisms or the populations in a habit..

    Schematic diagram of bacterial lactose operon
    Gene Action – Operon Hypothesis

    Learn how the way genes control and determine every aspect of the body. This lesson uses lac operon as an example. ..

    ..