7.1.6 Epistasis

• In dominant epistasis, one dominant allele at one locus masks the effect of all alleles at another locus
• Match the type of epistasis with its definition:

  Dominant Epistasis ↔️ One dominant allele masks others

  Recessive Epistasis ↔️ Two recessive alleles mask others
• In dominant epistasis, the expected phenotypic ratio is 9:3:3:1
• Epistasis is a phenomenon where the expression of one gene affects or masks the expression of another gene at a different locus
• In recessive epistasis, two recessive alleles at one locus mask the effect of alleles at another locus
• Epistasis causes deviations from the typical 9:3:3:1 phenotypic ratio due to gene masking
• In epistasis, one gene affects the expression of another gene at a different locus
• What genotype in humans results in albinism due to recessive epistasis?

  cc
• What is epistasis in genetics?

  One gene masks another
• What is the effect of recessive epistasis on other alleles?

  Masking by two recessives
• In mice, which allele is epistatic to the b allele in coat color determination?

  A
• What is the expected phenotypic ratio in recessive epistasis?

  9:3:4
• There are two main types of epistasis: dominant and recessive.


  True
• In mice, which allele is epistatic to the allele that determines coat spotting?

  A
• What is the expected phenotypic ratio in dominant epistasis?

  12:3:1
• Match the type of epistasis with an example:

  Dominant epistasis ↔️ Mice coat color

  Recessive epistasis ↔️ Human albinism
• Epistasis can alter the expected phenotypic ratios in inheritance.


  True
• Understanding epistasis is essential for interpreting inheritance patterns that do not follow Mendelian ratios.


  True
• In humans, the cc genotype results in albinism due to recessive epistasis.

  True
• Epistasis can only occur when genes are located on the same chromosome.

  False
• What type of epistasis occurs when one dominant allele masks the effect of all alleles at another locus?

  Dominant epistasis
• Understanding epistasis is crucial for interpreting inheritance patterns that do not follow typical Mendelian ratios.

  True
• Epistasis and multiple alleles are the same genetic phenomenon.

  False
• In humans, the secretor gene influences the expression of the ABO blood group system.
• In sweet peas, the homozygous recessive genotypes bb or pp always result in white flowers.

  True