To be like no one else - the task is certainly not simple, but sometimes quite honorable. However, if your unlikeness is only that you are absolutely white, then it's better to be like everyone else. After all, in our world, those who are very different from others are taken care of and considered a "white crow". Therefore, such individuals were called albinos, derived from the Latin word "albeus", which in translation means "white".
But in fact, albinism is not only a kind of "cosmetic" deffect, but also a genetically caused failure in the metabolism, leading to multiple "breakages" in the well-functioning work of the living organism.
However, in addition to pathologies, this kind of gene anomaly complicates the life of its carrier by depriving it of its masking cover, which makes the survival process in nature rather complicated. For example, how can you hunt and procure food, having a beautiful snow-white cover, so it gives out a possessor from a flock of natural coloring?
The reason for albinism lies in the fact that in the body of such animals does not produce pigments, known collectively as melanins (from the Greek "melanos" - "black"). This pigment really corresponds to its name and really has dark colors - from brown to black. But for a bright coloring is responsible for a group of melanins containing sulfur, and these colors vary in a fairly wide range - from yellow to red. And although, of course, the animals have other types of pigments, but it is the concentration, the correct ratio and the peculiarities of the mutual arrangement of the granules in the cover of their carrier, and they create an excellent coloring for the representatives of the animal world.
If you did not skip biology lessons in elementary school, then you probably should know that the body cells of animals like humans contain a pair of genes: the first half from the mother, the second half from the father. The genes responsible for the alternative manifestation of the same feature are called alleles and are located in the same region of homologous chromosomes. But with all this they can not be the same, that is, one pair of genes - the dominant ones will suppress the other pair - the recessive ones.
So if an individual inherited both of these from his parents, then such a set of genes is considered normal. And since the normal gene is dominant in relation to the gene of albinism, then in this case the synthesis of melanin will be completed and albinism does not appear in outward appearance. But if the individual receives from each parent for the gene of albinism, then in this case melanin in such an organism will not be developed. Proceeding from this, it can be concluded that the white color of albinos is not at all a coloring - but its complete absence.
These albinos are fundamentally different from other wild animals dressed in snow-white cover. In fact, unlike albinos, snow-white colors such as polar bears or owls were obtained by them from nature. Melanin in their body is produced exactly as much as they need for normal life, and those tissues and organs that are supposed to contain pigments according to the nature plan, they are intensely colored.
Full albinos are dressed in white wool or feathers, they have white skin, scales, beaks, claws, horns and hoofs, and even the eyes have a reddish hue, because through the discolored iris, the vascular membrane of the eye penetrated through the blood capillaries.
Albinos can be found among many species of wild animals. However, the albinos devoid of masking cover stand out very sharply among their relatives, becoming easy prey for predators. But predators, albinos can not stealthily creep up to the victims and get their own food. Also, we should not forget that the "impressive" appearance plays an important role in the marital relations of not only humans but also animals, so that faded albino males can hardly win the favor of females of their kind preferring intensely colored males.
It is also well known that melanins are able to absorb most of the rays of the solar spectrum, and play the role of filters that protect the skin from excess of solar radiation, including from ultraviolet rays, deadly for cellular structures and DNA. More recently, scientists who drew attention to the increased pigmentation of the skin at the site of healing wounds and burns, have proved that the role of melanins is not reduced to photodisection of integuments. Apparently, they take an active part in eliminating the consequences of any stressful action that violates cellular homeostasis, and they are important part of the body's immune system as a whole.
Melanin is also needed for normal functioning of such important sensory organs as vision and hearing. A layer of dark pigment protects the photosensitive cells of the retina and increases the clarity of the resulting image, absorbing unnecessary light and extinguishing reflections reflected from the inner surface of the eye. In the inner ear, melanocytes are contained in the so-called vascular band that produces endolymph, which fills the cavity of the ear snail. Without them (or with their lack), the endolymph changes its ionic composition, which affects the acuity of hearing. To some extent, poorly heard and albino animals, and people albino.
During embryonic development, melanocytes are laid in the so-called neural crest of the embryo, from which most of the bones and cartilage of the skull, middle ear, larynx, sensory cells of the sense organs form. Therefore, disturbances in the development of melanocytes are often accompanied by such serious pathologies in the structure of tissues and organs that albino embryos die in the early stages of development. Most albinos who manage to safely be born are extremely sensitive to solar radiation, have vision and hearing problems and, as a rule, die at a rather early age from infections that their weakened immune system is not able to cope with.
