L6: Gene Interactions II Flashcards
Define epistasis
When one gene affects the expression of another gene
What ratio shows complementary gene action between 2 genes?
9:7
Describe complementary gene action
- Both genes required for a phenotype
What ratio shows recessive epistasis between 2 genes?
9:3:4
How many genes typically control traits like coat color in mice?
Multiple genes
Describe recessive epistasis
1 gene (recessive) masks the effect of another gene
Describe dominant epistasis
A dominant allele masks another gene’s expression
What ratio shows dominant epistasis between 2 genes?
12:3:1
Describe duplicate gene action
2 genes performing the same function
What ratio shows duplicate gene action between 2 genes?
15:1
How many genes control coat colour in mice?
At least 5 genes
Define allelism
Relationship between 2 or more different forms of a gene (alleles) that occupy the same position on a specific chromosome
What is the purpose of the complementation test in genetics?
To determine if two mutations are in the same gene
What does a 9:3:4 phenotypic ratio indicate about gene interaction?
Recessive epistasis
What is the significance of establishing complementation groups in genetics?
Determining the number of genes for a function
What does a 12:3:1 ratio suggest about the relationship between two genes?
The genes are interacting
How does the presence of one dominant allele mask the effects of another gene’s genotype?
Through complete dominance
What happens when recessive mutations represent alleles of the same gene during complementation testing?
The phenotype remains mutant.
What is an example of recessive epistasis in coat color production in mice?
Two “e” alleles masking “b” and “a” alleles
How can the complementation test be used to determine how many genes control a characteristic?
If the F1 generation exhibits a wild-type phenotype, a single gene controls the characteristic
How does the number of complementation groups relate to the number of mutated genes?
The number of complementation groups =
the number of mutated genes
What is the complementation test used for?
Determine the no. of genes involved in a trait
Describe the process of the complementation test
1) Induce mutations that affect phenotype we want to investigate
2) Cross mutants together
Wild-type phenotype reappear- mutation affect different genes
Mutant phenotype remains- mutation affect same gene
