Epistasis Flashcards
What’s epistasis
When the allele of a gene affects/masks (hides) the expression of another allele in the organisms phenotype
What can epistasis slyer, just like linkage
The theoretical ratios predicted by Mendel
E.g of epistasis
Mice
Gene 1 - controls distribution of melanin (banded or not)
A- hairs with black bands
aa- black hairs
Gene 2- controls colour of hairs by controlling if gene 1 is expressed or not. It controls melanin production
B- melanin production in hair
bb- no melanin production so mouse is white (albino)
3 types of epistasis
Dominant
Recessive
Complementary
What’s dominant epistasis
When only 1 copy is needed to mask the expression of another
What’s recessive epistasis
when 2 copies are needed to mask the expression of another
What’s complimentary epistasis
When the effect of 1 gene is combined with the effect of another to determine if the phenotype is expressed
What must be inherited in complementary epistasis to express the phenotype
at least 1 dominant allele of each gene
E.g of dominant epistasis
Squash\
What is complementary epistasis similar to
Explain
Similar to recessive epistasis
2 recessive alleles are needed to block the expression of a phenotype controlled by another gene
E.g 1 of complementary epistasis
Sweet pea plants
What is needed to complete chemical pathway in complementary epistasis
Both enzymes A and B
E.g 2 of complementary epistasis
Red hair
Inheritance of another gene can block MC1R protein so no eumelanin is made (red pigment produced instead)
