Interacting Genes & Epistasis - entries for “causal” explanations
2/17/16
The “old” (existing) explanations follow the ratio&genotype. The new causal ones are bold & underlined.
9:7 – Duplicate recessive epistasis
9 Runner A-BA 9 ratio must include at least 1 dominant allele of both genes.
A Dominant allele at BOTH genes is REQUIRED to produce Runners.
7 Bunch aa--,--bb
A 7 ratio includes two recessive alleles at either or both genes.
Two recessive alleles at either gene BLOCKS the production of Runners.
9:4:3 – Recessive epistasis
9
A-BA 9 ratio must include at least 1 dominant allele of both genes.
A Dominant allele at BOTH genes is REQUIRED to produce the phenotype.
4
aa-NO MENU
Homozygous recessive at gene A BLOCKS expression of gene B.
12:3:1 – Dominant epistasis
12 White
A--A 12 ratio must include at least one dominant allele of one gene and any in the other.
Dominant allele at gene A BLOCKS the production of pigment determined in B.
3 Yellow
A-bb A 3 ratio has at least 1 dominant allele for 1 gene and only recessive for the other.
Expression of gene A is BLOCKED by B.
15:1 Duplicate genes - Color in Wheat
15
A---, --BA 15 ratio includes at least one dominant allele for EITHER gene.
A dominant allele at EITHER gene is REQUIRED to produce color in Wheat.
13:3 – Dominant suppression
13 No-Mal --B-, aabb NO MENU
Dominant allele at gene A BLOCKS gene B, which requires dominant allele.
3 Malvidin A-bb
A 3 ratio has at least 1 dominant allele for 1 gene and only recessive for the other.
Expression of gene A is BLOCKED by B. Hmm… No-Mal implies blockage…?
9:6:1
9 Disk
A-B-
6 Sphere aaB-, A-bb
1 Long
aabb
A 9 ratio must include at least 1 dominant allele of both genes.
A Dominant allele at BOTH genes is REQUIRED to produce the disk shape.
A 6 ratio includes at least one dominant allele for EITHER gene, but NOT both.
Dominant allele at either gene results in less of a disk – a sphere.
No dominant alleles result in ??
Old explanations:
A 9 ratio must include at least 1 dominant allele of both genes.
A 3 ratio has at least one dominant allele for one gene and only recessive alleles for the other.
A 1 ratio must be homozygous recessive for both genes A and B.
A 12 ratio must include at least one dominant allele of one gene and any alleles in the other.
A 15 ratio includes at least one dominant allele for EITHER gene.
A 6 ratio includes at least one dominant allele for EITHER gene, but NOT both genes.
A 7 ratio includes two recessive alleles at either or both genes.