The color of hay: the peasants of Maramureş

The color of the skin is influenced by a number of pigments, including melanin, carotene, and hemoglobin. Recall that melanin is produced by cells called melanocytes, which are found scattered throughout the stratum basale of the epidermis. The melanin is transferred to the keratinocytes via melanosomes.
Melanin occurs in two primary forms: eumelanin that provides black and brown pigment and pheomelanin that provides red color. Dark-skinned individuals produce more melanin than those with pale...

Mortar, a mixture of Portland cement, hydrated lime, sand, and water, is a crucial binding material in construction. Its primary function is to join masonry units together, filling gaps and ensuring a uniform distribution of weight across the structure. This helps in preventing potential weaknesses. Mortar also serves as a protective barrier against environmental elements such as water and wind, thereby safeguarding the interior of the structure. It also compensates for surface irregularities...

In addition to multiple alleles at the same locus influencing traits, numerous genes or alleles at different locations may interact and influence phenotypes in a phenomenon called epistasis. For example, rabbit fur can be black or brown depending on whether the animal is homozygous dominant or heterozygous at a TYRP1 locus. However, if the rabbit is also homozygous recessive at a locus on the tyrosinase gene (TYR), it will have an unshaded coat that appears white, regardless of its TYRP1...