GENE 303 L5

Dominance in heterozygotes

condition in which a heterozygote expresses a trait in the

same manner as the homozygote dominant

• property of a pair of alleles in relation to a particular phenotype

incomplete dominance

phenotype of heterozygote is almost meeting in the middle of the dominant and recessive phenotypes

dominant = red, recessive = white, pink = co dominance

what is the relatonship between IA, IB, and IO blood groups

IA and IB are codominant to each other

IO is recessive to both IA and IB

epistasis

genetic interaction between genes in which the genotype at one locus affects the phenotypic expression of the genotype at another locus

what is the phenotypic ratio of 2 phenotypic classes when there is epistasis

9:7

what is a mutant screen

genetic experiment aimed at isolation of multiple new mutations (genes and or alleles) that affect a specific trait

complementation test

the phenomenon in which two recessive mutations with similar phenotypes result in wildtype phenotypes

• for example, recessive mutation in a gene that produces enzyme to make flower pigment, causing it to stay white even though its genotype for that is not recessive

for complementation test, if mutant strain 1 and mutant strain 2s offspring is still white, what does that indicate? what does it indicate if its purple?

if it is white, that indicates noncomplementation and that the mutation 1 and mutation 2 are defects in the same gene as neither of them provided a proper copy to the offspring

• if its purple, this indicates complimentation and that mutation 1 and mutation 2 are defects on different genes and both provided a working copy to the offspring

what is a complementation group

the category label for the mutations that behave as if they’re in the same gene, meaning that when theyre crossed, they fail to compliment each other