Part J: Lecture 28 Flashcards
F2 ratio of dihybrid intercross
9:3:3:1
If F2 ratio of dihybrid intercross is not 9:3:3:1 then ___
gene interaction
no gene interaction (def.)
when two gene independently contribute to a single phenotype (ex. corn snakes)
no gene interaction F2 ratio
9:3:3:1
If we a see a 9:3:3:1 phenotypic ratio in F2, it means… genes? chromosomes? interaction?
two genes
autosomal
on different chromosomes
no gene interaction
order when determining genotypes of generation
F1 -> F2 -> P
no gene interaction biochemical pathway
separate biochemical pathways
complementary genes (def.)
when two genes are both needed to produce a WT phenotype (ex. petal colour in harebells)
complementary genes F2 ratio
modified 9:3:3:1 ratio
If we a see a modified 9:3:3:1 phenotypic ratio in F2, it means… genes? chromosomes? interaction?
two genes
autosomal
on different chromosomes
there is gene interaction
genetic interactions (2)
allele interactions
gene interactions
complementary genes statement
gene 1 and gene 2 show complementary gene action
complementary genes biochemical pathway
-two enzymes in the same pathway
-two subunits of one enzyme
duplicate genes (def.)
when either of two genes is needed to produce a WT phenotype (ex. seed coat colour in wheat)
duplicate genes biochemical pathway
one pathway needs protein A or protein B
discontinuous variation (def.)
when a character is found in two or more distinct forms in a population (2 seed colours in peas)
continuous variation (def.)
when a character is found in a range of forms in a population (multiple hair colours in humans)
continuous variation: one gene
3 phenotypic ratios
continuous variation: two genes
5 phenotypic ratios
continuous variation: three genes
can’t distinguish categories
dominance (def.)
when one allele conceals another allele
epistasis (def.)
when one gene conceals another gene
Recessive epistasis
when the recessive phenotype of one gene conceals phenotype of second gene
recessive epistasis statement
gene A is recessively epistatic to gene B
recessive epistasis biochemical pathway
same linear pathway
dominant epistasis
when the dominant phenotype of one gene conceals the phenotype of another gene
dominant epistasis biochemical pathway
branched pathway
linear pathway –> ____ epistasis
recessive
branched pathway –> ____ epistasis
dominant
5 types of gene interactions
none (A and B are independent)
complementary genes (A + B = wt)
duplicate genes (A or B = wt)
recessive epistasis (a/a masks B-gene)
dominant epistasis (A/__ masks B-gene)
