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Lecture 4

ARCL-1006EL Lecture 4: Human Biological Vairations Jan 24 4

by OneClass2472028 , Winter 2018
3 Pages
12 Views
Winter 2018

Department
Environment
Course Code
ARCL-1006EL
Professor
Alice Hawkins
Lecture
4

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

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Description
ARCL 1006 Jan 24, 2018 Human Biological Variation Race Cline: gradual change in frequency or occurrence of something over space Contributors to variation in skin colour Oxidized hemoglobin (red, from red blood cells) melanin produced by melanocytes in epidermis MC1R coded gene skin colour is polygenic not a mendelian trait. There are several genes that contribute to skin colour Advantages of dark coloured skin in low latitudes (close to equator higher amounts of UVR) ultraviolet radiation sunburn, skin cancer Meaning blocks UVR Ex) skin cancer males in Britain 28:100,000 males in australia 265: 100,000 Folate (B Vitamin) needed for DNA synthesis ad cell replication exposure to UVR breakdown of folate Melanin helps lter out UVR preventing breakdown of folate lack of folate cause birth defects Advantages of light coloured skin in high latitudes Vitamin D needed for calcium metabolism for normal development of bones and teeth UVR causes a reaction in the skin that leads to production of vitamin D Lack of vitamin D RICKETS rate of rickets in the 1920s for African American children 23x higher than for European American children Ability to produce lactase in adulthood Lactase necessary to break up lactose into glucose and galactose lactose sugar made up of two smaller sugars Another example of a cline Frequency of the alleles A, B, O for blood groups in humans. Neutral human genetic variation Arises largely from genetic drift
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