7.1.6 Epistasis

• Epistasis refers to a genetic interaction where the expression of one gene is modified by one or more other genes
• In dominant epistasis, a homozygous recessive allele masks the effect of another gene.

  False
• In dominant epistasis, what phenotypic ratio results from one or two copies of the dominant allele masking another gene's effect?

  12:3:1
• Recessive epistasis occurs when a dominant allele masks the effect of another gene.

  False
• In recessive epistasis, homozygous recessive alleles mask the effect of another gene
• What is the role of modifier genes in epistasis?

  Affect phenotypic effect
• In dominant epistasis, the hypostatic gene is the gene whose expression is masked.


  True
• Match the type of epistasis with its definition:

  Dominant Epistasis ↔️ Dominant allele of one gene masks the other

  Recessive Epistasis ↔️ Homozygous recessive of one gene masks the other

  Duplicate Recessive Epistasis ↔️ Two genes' recessive alleles each mask the other
• The epistatic gene is the gene whose expression is masked or modified.

  False
• A hypostatic gene is one whose expression is masked or modified
• In epistasis, genes interact
• A hypostatic gene is masked or modified by the epistatic gene.
• In dominant epistasis, the epistatic gene contains a dominant allele
• Give an example of recessive epistasis.

  Homozygous cc in plants
• In duplicate recessive epistasis, two genes each have a recessive allele that masks the effect of another gene.
• In epistasis, multiple genes interact to determine a single phenotype.


  True
• The phenotypic effect of one gene in epistasis depends on modifier genes.


  True
• Recessive epistasis results in a phenotypic ratio of 9:3:4.
• In Labrador retrievers, the E gene determines if coat color is expressed, an example of dominant epistasis.


  True
• In dominant epistasis, the phenotypic ratio is 12:3:1
• In recessive epistasis, the phenotypic ratio is 9:3:4
• What is the phenotypic ratio in dominant epistasis when one or two copies of the dominant allele mask another gene?

  12:3:1
• In epistasis, the phenotypic effect of one gene depends on the presence of modifier genes.


  True
• In dominant epistasis, the epistatic gene is the dominant allele
• What is the phenotypic ratio in dominant epistasis when the dominant allele masks the effect of another gene?

  12:3:1
• In epistasis, multiple genes interact to determine a single phenotype
• In dogs, what genotype of the E/e gene results in a yellow coat regardless of the B/b gene?

  ee
• Epistasis refers to a genetic interaction where one gene modifies the expression of another gene.


  True
• What is an epistatic gene?

  A gene that masks another
• What is epistasis?

  Genetic interaction modifying expression
• The phenotypic ratio in dominant epistasis is 12:3:1
• In recessive epistasis, homozygous recessive alleles of one gene mask the effect of another gene.


  True
• What is the phenotypic ratio in duplicate dominant epistasis?

  15:1
• An epistatic gene masks or modifies the expression of a hypostatic gene.
• In dominant epistasis, the phenotypic ratio is 12:3:1.
• In which organism is complementary gene action observed for flower color?

  Snapdragons