Chapter 4 - Gene Interaction

Question 1

epistasis definition

Answer 1

alleles of one gene make the phenotypic effects of the alleles of a different gene

Question 2

incomplete penetrance

Answer 2

occurs when a dominant phenotype is not expressed even though an individual carries a dominant allele

Question 3

pleiotropy

Answer 3

one gene thats affects many physiological processes throughout the life cycle

Question 4

penetrance

Answer 4

frequency at which al allele manifests itself phenotypically within a population

Question 5

expressivity

Answer 5

degree of phenotypic manifestation of a genotype in a particular individual

Question 6

haploinsufficient

Answer 6

a wild type allele that is unable to support wild type function in heterozygous organisms (recessive wild type)

Question 7

dihybrid phenotype ratio for recessive epistasis

Answer 7

9:3:4

Question 8

dihybrid phenotype ratio for dominant epistasis

Answer 8

12:3:1

Question 9

dihybrid phenotype ratio for duplicate recessive epistasis

Answer 9

9:7

Question 10

genetic complementation

Answer 10

occurs when mutant organisms carry mutations of different genes that produce the same abnormal phenotype

Question 11

complementation test (or cis-trans)

Answer 11

cross true-breeding mutant with same phenotype to each other

Question 12

trans-complementation

Answer 12

if F1 is wild type, the mutations are not alleles of the same gene, so mutations in 2 different genes affect the same trait