Everything about Biological Pigment totally explained
In
biology, a
pigment or
biochrome is any material resulting in
color of plant or animal cells, which is the result of selective
color absorption. Many biological structures, such as
skin,
eyes,
fur and
hair contain pigments (such as
melanin) in specialized cells called
chromatophores.
Pigment color differs from
structural color in that it's the same for all viewing angles, whereas structural color is the result of selective
reflection or
iridescence, usually because of multilayer structures. For example,
butterfly wings typically contain structural color, although many butterflies have cells that contain pigment as well.
Biological pigments
Pigments in plants
Among the most important molecules for plant function are the
pigments. Plant pigments include a variety of different kinds of molecules, including
porphyrins,
carotenoids, and
anthocyanins. All biological pigments selectively absorb certain
wavelengths of
light while
reflecting others. The light that's absorbed may be used by the plant to power
chemical reactions, while the reflected wavelengths of light determine the
color the pigment will appear to the eye. Pigments also serve to attract
pollinators.
Chlorophyll is the primary pigment in plants; it's a
porphyrin that absorbs red and blue wavelengths of light while reflecting
green. It is the presence and relative abundance of cholophyll that gives plants their green color. All land plants and
green algae possess two forms of this pigment: cholorphyll
a and cholorphyll
b.
Kelps,
diatoms, and other photosynthetic
heterokonts contain chlorophyll
c instead of
b, while
red algae possess only chlorophyll
a. All chlorophylls serve as the primary means plants use to intercept light in order to fuel
photosynthesis. chlorophyll is the reason most plants are of the colour green.
Carotenoids are red, orange, or yellow
tetraterpenoids. They function as accessory pigments in plants, helping to fuel
photosynthesis by gathering wavelengths of light not readily absorbed by chlorophyll. The most familiar carotenoids are
carotene (an orange pigment found in
carrots),
lutein (a yellow pigment found in fruits and vegetables), and
lycopene (the red pigment responsible for the color of
tomatoes). Carotenoids have been shown to act as
antioxidants and to promote healthy
eyesight in humans.
Anthocyanins (literally "flower blue") are
water-soluble flavonoid pigments that appear red to blue, according to
pH. They occur in all
tissues of higher plants, providing color in
leaves,
stems,
roots,
flowers, and
fruits, though not always in sufficient quantities to be noticeable. Anthocyanins are most visible in the
petals of flowers, where they may make up as much as 30% of the dry weight of the tissue. They are also responsible for the purple color seen on the underside of tropical shade plants such as
Tradescantia zebrina; in these plants, the anthocyanin catches light that has passed through the leaf and reflects it back towards regions bearing chlorophyll, in order to maximize the use of available light.
Betalains are red or yellow pigments. Like anthocyanins they're water-soluble, but unlike anthocyanins they're
indole-derived compounds synthesized from
tyrosine. This class of pigments is found only in the
Caryophyllales (including
cactus and
amaranth), and never co-occur in plants with anthocyanins. Betalains are responsible for the deep red color of
beets, and are used commercially as food-coloring agents.
Pigments in animals
Pigments in animals may serve to protect tissues from
ultraviolet radition, such as
melanin in the skin. Pigments may also aid in sexual reproduction, identifying species and gender of animals to potential mates, or signalling readiness to breed.
Some
cephalopods use pigmented
chromatophores to communicate.
Pigmentation is used by many animals for protection, by means of camoflauge, mimicry, or warning coloration. Camilions also use pigments to blend into surrounds because they can control the absorption level of the electromagnetic spectrum.
Diseases and conditions
A variety of diseases and abnormal conditions that involve pigmentation arise in humans and animals, either from absence of or loss of pigmentation or pigment cells, or from the excess production of pigment.
Albinism is an inherited disorder characterized by total or partial loss of melanin. Humans and animals that suffer from albinism are called "albinistic" (the term "albino" is also sometimes used, but may be considered offensive when applied to people).
Lamellar ichthyosis, also called "fish scale disease", is an inherited condition in which one symptom is excess production of melanin. The skin is darker than normal, and is characterized by darkened, scaly, dry patches.
Melasma is a condition in which dark brown patches of pigment appear on the face, influenced by hormonal changes. When it occurs during a pregnancy, this condition is called the mask of pregnancy.
ocular pigmentation is an accumulation of pigment in the eye, and may be caused by latanoprost medication.
Vitiligo is a condition in which there's a loss of pigment-producing cells called melanocytes in patches of skin.
Commercial uses
Pigments may be extracted and used as dyes.
Further Information
Get more info on 'Biological Pigment'.
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