Lecture 3f: Non-Allelic Interactions Flashcards
the process by which the expression of two or more genes influences one another in different ways as an organism develops a single characteristic. The majority of the traits that comprise living beings are coordinated by various genes.
gene interaction
an alternate form of a gene in which the alleles that affect a particular character are present at the same locus of the gene
allelic gene
an alternate form of a gene in which the alleles that affect a particular character are present at different loci of the gene
non-allelic gene
location: On the same location of the homologous chromosome
effects: Could form lethal genes and cause death
allelic gene
gene interaction types of allelic genes
Incomplete dominance, lethal factor, multiple alleles, etc.
location: On different locations of the homologous chromosome
effect: Could not affect phenotypes but cause an inhibitory effect on other non-allelic genes
non-allelic gene
gene interaction types in non-allelic genes
Simple interaction, complementary factor, epistasis, inhibitory factor, etc.
classical ratio of allelic/non-allelic gene interaction
3:1 or 9:3:3:1
- Interaction between alleles at different genes (loci) can result in Epistasis
- Can have varying effects on the phenotype
Non-Allelic/Epistatic gene interaction
Novel Phenotype ratio
9:3:3:1
New phenotypes result from interaction between dominants; and also from interaction from homozygous recessives.
novel phenotype 9:3:3:1
There is complete dominance of both gene pairs, but either recessive
homozygote recessive is epistatic to the effects of the other gene
complementary gene action 9 : 7
complementary gene action ratio
9 : 7
Homozygote is epistatic to the effects of the other gene.
complementary gene action 9 : 7
duplicate gene action ratio
15:1
There is complete dominance at both gene pairs, but either gene when dominant, is epistatic to the other
duplicate gene action 15:1
There is complete dominance at both gene pairs, but one gene when homozygous recessive, masks the effect of the other
recessive epistasis 9:3:4
recessive epistasis ratio
9:3:4
There is complete dominance at both gene pairs, but one gene, when dominant masks the effect of the other.
Dominant Epistasis 12:3:1
- dominant epistasis ratio
12:3:1
There is complete dominance at both gene pairs, but one gene, when dominant masks the effect of the other.
dominant epistasis
- dominant epistasis ratio
13:3
- There is complete dominance at both gene pairs, but one gene when dominant, is epistatic to the second.
- The second gene, when homozygous recessive, is epistatic to the first.
dominant recessive 13:3
non-allelic gene interactions
- novel phenotype (9:3:3:1)
- complementary gene action (9:7)
- duplicate gene action (15:1)
- recessive epistasis (9:3:4)
- dominant epistasis (12:3:1)
- dominant epistasis (13:3)
example of novel phenotype
chicken combs
example of complementary gene action
petal colors in sweat pea flowers
examples of recessive epistasis
- coat color in mice
- onion bulb color
- labrador dog coat color
example of dominant epistasis (12:3:1)
fruit color in squash
example of dominant epistasis (13:3)
feather color in fowl (chicken breeds)
example of duplicate gene action
shape of seed capsule in Sheperd’s purse
the inheritance of one gene does not influence the inheritance of the other gene.
law of independent assortment
Each genotype results in a unique phenotype
novel phenotype
At least one dominant allele from each of the two genes needed for phenotype
Complementary gene action
Homozyous recessive genotype at one locus masks expression at second locus
recessive epistasis
Dominant allele at one locus masks expression at second locus
dominant epistasis
One dominant allele from either of two genes needed for phenotype
duplicate gene action
