ANT202H5 Lecture Notes - Lecture 14: Cystic Fibrosis, Melanosome, Sunburn
Document Summary
Lactose in milk can substitute for vitamin d in facilitating calcium absorption in small intestines. People have to cover up to stay warm. Most common inherited disease in eu children (1/2000 births) Cftr mutation maintained because of natural selection: heterozygote advantage. Homozygous normal alleles: more susceptible to salmonella typhi. Widespread incidence of typhoid fever through eu history: before antibiotics killed up to 15% of infected. Skin color mainly due to pigment melanin. Produced by melanocytes = specialized epidermal cells. Synthesized in organelles = melanosomes: then transferred through dendritic structures to surrounding keratinocytes in epidermis, tyrosinase = key enzyme in melanin synthesis. # of melanocytes are similar in all populations. 2 types of melanin: eumelanin: brown/black, pheomelanin: red/yellow. #, size, distribution of melanosomes: light skin, melanosomes = small and packaged in groups, dark skin = more melanosomes, larger and packaged as a single entity. Near equator = high doses of uv radiation: tend to have darker skin.
