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OCA2
P protein, also known as melanocyte-specific transporter protein or pink-eyed dilution protein homolog, is a protein that in humans is encoded by the oculocutaneous albinism II (''OCA2'') gene. The P protein is believed to be an integral membrane protein involved in small molecule transport, specifically of tyrosine - a precursor of melanin. Certain mutations in OCA2 result in type 2 oculocutaneous albinism. OCA2 encodes the human homologue of the mouse p (pink-eyed dilution) gene. The human OCA2 gene is located on the long arm (q) of chromosome 15, specifically from base pair 28,000,020 to base pair 28,344,457 on chromosome 15. Function OCA2 provides instructions for making the protein called P protein which is located in melanocytes which are specialized cells that produce melanin, and in the cells of the retinal pigment epithelium. Melanin is responsible for giving color to the skin, hair, and eyes. Moreover, melanin is found in the light-sensitive tissue of the retina of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eye Color
Eye color is a polygenic phenotypic character determined by two distinct factors: the pigmentation of the eye's iris and the frequency-dependence of the scattering of light by the turbid medium in the stroma of the iris. In humans, the pigmentation of the iris varies from light brown to black, depending on the concentration of melanin in the iris pigment epithelium (located on the back of the iris), the melanin content within the iris stroma (located at the front of the iris), and the cellular density of the stroma. The appearance of blue, green, and hazel eyes results from the Tyndall scattering of light in the stroma, a phenomenon similar to that which accounts for the blueness of the sky called Rayleigh scattering. Neither blue nor green pigments are ever present in the human iris or ocular fluid. Eye color is thus an instance of structural color and varies depending on the lighting conditions, especially for lighter-colored eyes. The brightly colored eyes of many bird ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eye Color
Eye color is a polygenic phenotypic character determined by two distinct factors: the pigmentation of the eye's iris and the frequency-dependence of the scattering of light by the turbid medium in the stroma of the iris. In humans, the pigmentation of the iris varies from light brown to black, depending on the concentration of melanin in the iris pigment epithelium (located on the back of the iris), the melanin content within the iris stroma (located at the front of the iris), and the cellular density of the stroma. The appearance of blue, green, and hazel eyes results from the Tyndall scattering of light in the stroma, a phenomenon similar to that which accounts for the blueness of the sky called Rayleigh scattering. Neither blue nor green pigments are ever present in the human iris or ocular fluid. Eye color is thus an instance of structural color and varies depending on the lighting conditions, especially for lighter-colored eyes. The brightly colored eyes of many bird ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skin Color
Human skin color ranges from the darkest brown to the lightest hues. Differences in skin color among individuals is caused by variation in pigmentation, which is the result of genetics (inherited from one's biological parents and or individual gene alleles), exposure to the sun, natural and sexual selection, or all of these. Differences across populations evolved through natural or sexual selection, because of social norms and differences in environment, as well as regulations of the biochemical effects of ultraviolet radiation penetrating the skin. The actual skin color of different humans is affected by many substances, although the single most important substance is the pigment melanin. Melanin is produced within the skin in cells called melanocytes and it is the main determinant of the skin color of darker-skin humans. The skin color of people with light skin is determined mainly by the bluish-white connective tissue under the dermis and by the hemoglobin circulating in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oculocutaneous Albinism
Oculocutaneous albinism is a form of albinism involving the eyes ('' oculo-''), the skin (''-cutaneous''), and the hair. Overall, an estimated 1 in 20,000 people worldwide are born with oculocutaneous albinism. OCA is caused by mutations in several genes that control the synthesis of melanin within the melanocytes. Seven types of oculocutaneous albinism have been described, all caused by a disruption of melanin synthesis and all autosomal recessive disorders. Oculocutaneous albinism is also found in non-human animals. Types The following types of oculocutaneous albinism have been identified in humans. See also * Piebaldism * List of skin conditions * List of cutaneous conditions associated with increased risk of nonmelanoma skin cancer There are several conditions of or affecting the human integumentary system that are associated with an increased risk of developing nonmelanoma skin cancer (i.e. squamous-cell carcinoma and basal-cell carcinoma). See also * List of c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HERC2
HERC2 is a giant E3 ubiquitin protein ligase, implicated in DNA repair regulation, pigmentation and neurological disorders. It is encoded by a gene of the same name belonging to the HERC family, which typically encodes large protein products with C-terminal HECT domains and one or more RCC1-like (RLD) domains. History HERC2, previously referred to as the ''rjs'' gene locus, was first identified in 1990 as the gene responsible for two phenotypes in mice: the runty, jerky, sterile (rjs) phenotype and the juvenile development and fertility-2 (Jdf2) phenotype. Mutant alleles are known to cause hypo-pigmentation and pink eye phenotypes, as well reduced growth, jerky gait, male sterility, female semi-sterility, and maternal behaviour defects in mice. Gene locus The full ''HERC2'' gene is located at 15q13, encoded by 93 exons and its transcription is under the control of a CpG rich promoter. This region on chromosome 15 is susceptible to breaks during chromosomal rearrangement and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oculocutaneous Albinism
Oculocutaneous albinism is a form of albinism involving the eyes ('' oculo-''), the skin (''-cutaneous''), and the hair. Overall, an estimated 1 in 20,000 people worldwide are born with oculocutaneous albinism. OCA is caused by mutations in several genes that control the synthesis of melanin within the melanocytes. Seven types of oculocutaneous albinism have been described, all caused by a disruption of melanin synthesis and all autosomal recessive disorders. Oculocutaneous albinism is also found in non-human animals. Types The following types of oculocutaneous albinism have been identified in humans. See also * Piebaldism * List of skin conditions * List of cutaneous conditions associated with increased risk of nonmelanoma skin cancer There are several conditions of or affecting the human integumentary system that are associated with an increased risk of developing nonmelanoma skin cancer (i.e. squamous-cell carcinoma and basal-cell carcinoma). See also * List of c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melanin
Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino acid tyrosine is followed by polymerization. The melanin pigments are produced in a specialized group of cells known as melanocytes. Functionally, eumelanin serves as protection against Ultraviolet, UV radiation. There are five basic types of melanin: eumelanin, pheomelanin, neuromelanin, allomelanin and pyomelanin. The most common type is eumelanin, of which there are two types— brown eumelanin and black eumelanin. Pheomelanin, which is produced when melanocytes are malfunctioning due to derivation of the gene to its recessive format is a cysteine-derivative that contains polybenzothiazine portions that are largely responsible for the of red yellow tint given to some skin or hair colors. Neuromelanin is found in the brain. Research ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melanocyte
Melanocytes are melanin-producing neural crest-derived cells located in the bottom layer (the stratum basale) of the skin's epidermis, the middle layer of the eye (the uvea), the inner ear, vaginal epithelium, meninges, bones, and heart. Melanin is a dark pigment primarily responsible for skin color. Once synthesized, melanin is contained in special organelles called melanosomes which can be transported to nearby keratinocytes to induce pigmentation. Thus darker skin tones have more melanosomes present than lighter skin tones. Functionally, melanin serves as protection against UV radiation. Melanocytes also have a role in the immune system. Function Through a process called melanogenesis, melanocytes produce melanin, which is a pigment found in the skin, eyes, hair, nasal cavity, and inner ear. This melanogenesis leads to a long-lasting pigmentation, which is in contrast to the pigmentation that originates from oxidation of already-existing melanin. There are both ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Albinism
Albinism is the congenital absence of melanin in an animal or plant resulting in white hair, feathers, scales and skin and pink or blue eyes. Individuals with the condition are referred to as albino. Varied use and interpretation of the terms mean that written reports of albinistic animals can be difficult to verify. Albinism can reduce the survivability of an animal; for example, it has been suggested that albino alligators have an average survival span of only 24 hours due to the lack of protection from UV radiation and their lack of camouflage to avoid predators. It is a common misconception that all albino animals have characteristic pink or red eyes (resulting from the lack of pigment in the iris allowing the blood vessels of the retina to be visible), however this is not the case for some forms of albinism. Familiar albino animals include in-bred strains of laboratory animals (rats, mice and rabbits), but populations of naturally occurring albino animals exist in the wil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allele
An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution. ::"The chromosomal or genomic location of a gene or any other genetic element is called a locus (plural: loci) and alternative DNA sequences at a locus are called alleles." The simplest alleles are single nucleotide polymorphisms (SNP). but they can also be insertions and deletions of up to several thousand base pairs. Popular definitions of 'allele' typically refer only to different alleles within genes. For example, the ABO blood grouping is controlled by the ABO gene, which has six common alleles (variants). In population genetics, nearly every living human's phenotype for the ABO gene is some combination of just these six alleles. Most alleles observed result in little or no change in the function of the gene product it codes for. However, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid residue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skin
Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other cuticle, animal coverings, such as the arthropod exoskeleton, have different cellular differentiation, developmental origin, structure and chemical composition. The adjective cutaneous means "of the skin" (from Latin ''cutis'' 'skin'). In mammals, the skin is an organ (anatomy), organ of the integumentary system made up of multiple layers of ectodermal tissue (biology), tissue and guards the underlying muscles, bones, ligaments, and internal organs. Skin of a different nature exists in amphibians, reptiles, and birds. Skin (including cutaneous and subcutaneous tissues) plays crucial roles in formation, structure, and function of extraskeletal apparatus such as horns of bovids (e.g., cattle) and rhinos, cervids' antlers, giraffids' ossicones, armadillos' osteoderm, and os penis/os clitoris. All mammals have som ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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