Epistasis and Genetic Interactions

The video explains epistasis, where one gene affects the expression of another. It uses examples from plants, dogs, squash, and snails to illustrate recessive, dominant, and double recessive epistasis. The video highlights how genes interact in complex networks, affecting phenotypic outcomes.

What is epistasis?

• A type of genetic mutation

• A method of gene cloning

• A form of genetic recombination

• A process where one gene affects the expression of another

In the Arabidopsis example, what does the H gene influence?

• Root length

• Leaf shape

• Flower color

• Hair formation on the leaf surface

What is the expected phenotypic ratio in recessive epistasis for Labrador Retrievers?

• 9 black: 4 brown: 3 yellow

• 3 black: 9 brown: 4 yellow

• 4 black: 9 brown: 3 yellow

• 9 black: 3 brown: 4 yellow

In recessive epistasis, what happens if the big A protein is absent?

• The coat is white

• The coat is brown

• The coat is black

• The coat is yellow

What role does the A gene play in dominant epistasis in squash?

• It enhances the green pigment

• It converts green pigment into yellow

• It acts as a repressor blocking pigment accumulation

• It promotes pigment accumulation

What is the phenotypic ratio for dominant epistasis in squash?

• 4 white: 9 yellow: 3 green

• 3 white: 9 yellow: 4 green

• 9 white: 3 yellow: 4 green

• 12 white: 3 yellow: 1 green

In double recessive epistasis, what is required for the dark pigment to form in snails?

• Both A and B genes must be recessive

• Both A and B genes must be dominant

• Only the A gene must be dominant

• Only the B gene must be dominant

What is the phenotypic ratio for double recessive epistasis in snails?

• 1 dark: 3 albino

• 3 dark: 1 albino

• 7 dark: 9 albino

• 9 dark: 7 albino

In the context of epistasis, what does it mean when a gene is described as 'epistatic'?

• It is always dominant

• It is always recessive

• It masks the effect of another gene

• It is the only gene affecting a trait

What is the main takeaway about organisms and their traits from the video?

• Traits are solely influenced by environmental factors

• Traits are determined by a single gene

• Traits are independent of genetic interactions

• Traits depend on a chain of events controlled by different genes