Terms

Question 1

What is Epistasis

Answer 1

Effects of an allele from one gene, masking the effects of another gene.

Question 2

Recessive epistasis

Answer 2

When a recessive phenotype at one locus renders the function of another gene at another locus ineffective.

Question 3

Example of recessive epistasis and why it works the way it does:

Answer 3

Labrador retrievers come in 3 colors: choco brown, black, and yellow. This is due to the synthesis and deposition of 2 pigments Eumelanin and Pheomelanin.

When at locus one, the genotype is EE/Ee and at locus 2 the geno is BB/Bb, there is a black colour.

When the genotype is EE, Ee at locus one, eumelanin gets synthesized, and if at locus two the protein b is bb, then there is a brown color.

When the genotype is ee, no eumelanin gets synthesized and pheomelanin takes over and the labrador is yellow, regardless of what geno is at gene B.

Question 4

Eumelanin

Answer 4

Produces darker pigment color, black/brown.

Genotypes: EE/Ee/ee

Question 5

Pheomelanin

Answer 5

Produces lighter pigment colour, yellow.

Genotypes: BB/Bb/bb

Question 6

Recessive epistasis ratios

Answer 6

9:3:4 (last 3 r yellow B-ee, and 1 bbee)

Question 7

Dominant epistasis

Answer 7

When a dominant allele at one locus masks the function of an allele at another locus.

Question 8

Summer Squash

Answer 8

Gene A involved in catalyzing a reaction between green and yellow pigment.

Gene B involved in deposition.

When geno at A is AA/Aa, enzyme A converts green pigment to yellow, and if protein b has bb, then the pigment gets deposited.

When geno at A is aa, no coversion and green pigment gets deposited.

When there is BB/Bb at the second locus, no matter if u have AA/Aa/aa, the pigment doesn’t get deposited and the squash is white

Question 9

Dominant epistasis ratios

Answer 9

12 (white):3(yellow):1(green)

Question 10

Complementary Gene Interaction

Answer 10

P and C are required for purple color. Both cominant alleles have to be present at the same time for genotype to be expression.

Question 11

Complementary gene interaction ratios

Answer 11

9:7

Question 12

Dominant supression

Answer 12

Dominant allele at one gene specifically supresses the dominant allele of another gene.

L allele allows blue pigment, D allele suppresses it.

Question 13

Dominant suppression ratios

Answer 13

13:3