The Inheritance and Evolution of Skin Color
Genetic Level
Melanocortin 1 Receptor (MC1R) Gene
- function of MC1R
- G protein linked receptor
- effect of polymorphisms
- alleles
TYR, TYRP1, and TYRP2
Function of Melanin
- TYR gene: tyrosinase
- TYRP1 gene: tyrosinase related protein 1
- TYRP2 gene: tyrosinase related protein 2
Genetic Overview
- protects DNA
- visible light
- invisible: UVA and UVB
- too much sun exposure
- genetic damage
- skin cancer
Cellular Level
- complicated
- over 20 different genes involved
- TYR, TYRP1, TYRP2, SLC45A2, SLC24A5, OCA2, MC1R
SLC24A5
The Basics
- function
- NCKX5
- single nucleotide polymorphisms (SNPs)
- correlation with skin color
- skin structure
- melanin
- what is it?
- phenotype spectrum
- albinism
Pathway of Melanin
- melanocyte
- melanin production
- melanosome
- eumelanosomes vs pheomelanosomes
- keratinocyte
Formation of Melanin
Why does the level of UV radiation affect skin color?
Eumelanin vs. Pheomelanin
Conclusion
- color
- ratio
- function
- skin cancer
- folate (vitamin B6)
- Vitamin D
- positive selection
Overview
Evolution
- complicated inheritance
- polymorphisms account for variation
- different types of melanin produced
- small clan of humans in Africa
- migration only began 100,000 years ago
- UV exposure is main cause of skin color variation
Implications
- social impact
- scientific knowledge