MBG 1000 Lecture 9: MBG Lecture 9-10

• School: University of Guelph
• Department: Molecular Biology and Genetics
• Course: MBG 1000
• Professor: Georgevander Merwe

Document Summary

Pale eyes at birth; reduced retinal pigmentation; impaired optical nerve development; vision problems: oca type 1b (oca1b, phenotype: some low levels of pigmentation. Reduced activity of tyrosinase; gene carrier a mutation that reduces encoded tyrosinase activity. Hair colour varies from light yellow to light brown, light skin color; freckles. Pale eyes at birth, develops light-coloured eyes; reduced retinal pigmentation; impaired optical nerve development; vision problems. Individuals with classic albinism (oca1a) do not produce melanin: homozygous for a null allele of the tyrosinase gene (which encodes one of the enzymes needed to synthesize melanin) Individuals with oca1b (or cats of the himalayan and siamese breeds) are homozygous for a hypomorphic allele of the tyrosinase gene. Albinism & health risks: melanin protects cells against ultraviolet radiation, natural sunscreen, absorbs uv rays and repairs some uv-related cell damage, absence of melanin increases risk of various cancers, affected individuals must use sun protection measures.