Biology of Skin Color Verified A+
MC1R Allele - The MC1R allele is a receptor that activates the production of darker eumelanin pigment, as opposed
to lighter pheomelanin. - This allele is highly active in individuals of African descent, resulting in elevated eumelanin expression. - Research in...
- The MC1R allele is a receptor that activates the production of darker eumelanin pigment, as opposed
to lighter pheomelanin.
- This allele is highly active in individuals of African descent, resulting in elevated eumelanin expression.
- Research indicates that there is minimal genetic variation in the MC1R allele among African
populations.
Selection for Skin Color in Equatorial Africa
- There is negative selection against light skin color in equatorial Africa, meaning rare alleles that are
harmful are eliminated, favoring traits that enhance survival.
Impact of Folate Levels
- Reduced levels of folate, a water-soluble B vitamin, can lead to severe birth defects and decreased
sperm counts.
Relationship Between Folate and UV Exposure
- UV light decreases folate levels in the body.
Selection for Lighter Skin at Higher Latitudes
- In human populations that moved to areas with lower UV radiation, there was positive selection for
lighter skin, indicating the emergence of advantageous genetic variants.
Vitamin D Production and Skin Color Evolution
- The data suggest that the evolution of lighter skin was likely driven by the need for efficient vitamin D
synthesis, as lighter skin is better suited for producing vitamin D in conditions of lower UV radiation.
UV Index and Latitude Relationship
, - There is a clear relationship where increased UV radiation is found along the equator (0 degrees
latitude) and decreases toward the northern and southern poles; thus, the further one is from the
equator, the less intense the UV radiation.
Folate's Importance
- Folate is a crucial B vitamin essential for fetal development, and it is negatively impacted by UV light
unless melanin offers protective coverage.
Melanocytes and Keratinocytes
- Melanocytes, located in the lower epidermis, are responsible for producing melanin.
- Keratinocytes are found at the surface of the epidermis and provide protection from environmental
elements.
Melanosomes
- Melanosomes are organelles that contain melanin, which serves to shield the nucleus from damaging
UV radiation.
Functions of Melanin in Other Animals
- In addition to human traits, melanin serves various functions in other animals, such as providing
camouflage and aiding in temperature regulation.
Advantages of Skin Color Variations
- Lighter skin allows for improved production of vitamin D.
- Darker skin offers enhanced protection against harmful UV radiation.
Melanoma
- Melanoma is a common form of skin cancer that typically appears later in life.
Variability of Traits
- Traits that exhibit significant variability, similar to skin color, include eye color and hair color.
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