ARCL-1006EL Lecture Notes - Lecture 4: Human Genetic Variation, Ultraviolet, Calcium Metabolism
16 Jun 2018
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Department
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Professor
ARCL 1006
Jan 24, 2018
Human Biological Variation Race
ā¢Cline: gradual change in frequency or occurrence of something over space
ā¢Contributors to variation in skin colour
ā¢Oxidized hemoglobin (red, from red blood cells)
ā¢melanin produced by melanocytes in epidermis
ā¢MC1R- coded gene
ā¢skin colour is polygenic- not a mendelian trait. There are several genes that contribute to
skin colour
ā¢Advantages of dark coloured skin in low latitudes (close to equator // higher amounts of UVR)
ā¢ultraviolet radiation - sunburn, skin cancer
ā¢Meaning blocks UVR
ā¢Ex) skin cancer
ā¢males in Britain 28:100,000
ā¢males in australia 265: 100,000
ā¢Folate (B Vitamin) needed for DNA synthesis ad cell replication
ā¢exposure to UVR - breakdown of folate
ā¢Melanin helps ļ¬lter out UVR preventing breakdown of folate
ā¢lack of folate cause birth defects
ā¢Advantages of light coloured skin in high latitudes
ā¢Vitamin D needed for calcium metabolism for normal development of bones and teeth
ā¢UVR causes a reaction in the skin that leads to production of vitamin D
ā¢Lack of vitamin D - RICKETS
ā¢rate of rickets in the 1920s for African American children 2-3x higher than for European
American children
ā¢Ability to produce lactase in adulthood
ā¢Lactase- necessary to break up lactose into glucose and galactose
ā¢lactose- sugar made up of two smaller sugars
ā¢Another example of a cline-
ā¢Frequency of the alleles A, B, O for blood groups in humans.
ā¢Neutral human genetic variation
ā¢Arises largely from genetic drift
