Flashcards in Gene Interactions Deck (13):
What is epistasis?
An interaction between two different genes so that an allele of one of them interferes with or inhibits the phenotypic expression of the other
What is the gene which is inhibited/interfered with called?
What is duplicate recessive epistasis?
When a dominant allele at either of two loci can mask the expression of recessive alleles at the two loci
How would we know whether two true breeding lines carry mutations in the same gene or different genes?
1. Collect a population of independently isolated mutants showing the same mutant trait
2. Cross them in pairwise combinations
3. How many crosses produce mutant offspring and how many crosses produce wildtype offspring?
What is a recessive lethal gene?
Absence of a gene product leads to death in homozygotes
What is a dominant lethal gene?
Both homoxygotes and heterozygotes carrying the allele will die.
What is a sex-linked lethal gene?
Homozygotes of the homogametic sex will die - heterozygotes will survive unless they inherit one copy of the lethal allele.
What is penetrance?
If individuals show the expected phenotype the gene is said to have complete pentrance 100%
What is expressivity?
A certain mutant gene may affect the phenotype of an organism to a different degree
What is variable expressivity?
Where the gene is expressed above a threshold you will see a phenotype, below you will not see the phenotype
What is complementation?
aaBB and AAbb, alleles a and A are complementary as are alleles B and b in double recessive epistasis
When does complementation occur?
When two strains of an organism with different homozygous recessive mutations that produce the same mutant phenotype produce offspring with the wild-type phenotype when mated or crossed.