Topic 3 Gene Interactions Flashcards
How does the advanced nomenclature work for genes?
The WT allele is the same as mutant but with a plus: Ex. a+/a
The mutant is dom:
A/A+
What are lethal alleles
When two copies of a mutant alleles are inherited and it leads to death for the homozygote.
Y mutant: Y/Y dies (embryonic lethal)
Y/Y+ lives
What is penetrance
Incomplete/variable penetrance
% of ppl with mutation that show mutant phenotype
Some people have mutation genotype but don’t show mutation phenotype
What is expressivity
variable expressivity
Differing levels that a mutant phenotype is expressed
Some ppl show differing lvls of the mutant phenotype but it’s not due to more or less alleles
Why would ppl with same mutation not show same phenotype
Environment (things we eat/do)
Genetic background
Subtlety of mutant phenotype
What happens if a gene in that gene pathway of mutated
The phenotype is no longer WT
What an easy way to tell order of compounds in a pathway
The more mutants growing on a compound, the later it is in the pathway and vice versa
How to perform the complementation test
Set up mutant crosses with wt to check for which is recessive
Then cross each mutant to each other to test for complementation
How do you know if the mutation for each mutant are in the same gene
When doing complementation test, if the cross between the mutants gives the mutant phenotype, the mutations are in the same gene.
If the WT phenotype is shown then the mutant in each mutant are in diff genes and the complement
What is recessive epistasis
What the phenotype of one mutants allele (baldness) masks the phenotype of another mutant allele (curly hair)
We’d say bald is epistatic to curly
What are suppressor mutations
They reverse the effect of a mutation in another gene which results in the WT
Ex. Repression of a WT disease
Normal function is to turn off expression of disease gene, but mutation in suppressor causes WT disease protien to be made.
What are synthetic mutations
Mutation in two diff genes that occur together (ab instead of a+b+) do not cause WT phenotype
aB+: still WT a+B: still WT ab: not WT
15:1 WT to recessive ratio
