Chapter 3

Question 1

Multifactorial

Answer 1

Determined by two or more genes; interaction of genes with the environment ex) seed color of lentils

Question 2

Incomplete Dominance

Answer 2

hybrid does not represent either pure-breeding parent but an intermediate between those of the pure-breeding parents ex) red x white = pink

Question 3

Codominance

Answer 3

both traits show up equally in the heterozygote’s phenotype

Question 4

Multiple alleles

Answer 4

a given gene may have more than two alleles

Question 5

Dominance series

Answer 5

Alleles listed in order from most dominant to more recessive

Question 6

histocapability

Answer 6

plays a critical role in facilitating a proper immune response that destroys intruders while leaving the body’s own tissues interact

Question 7

mutations

Answer 7

alterations of the genetic materials, causes multiple alleles of an allelic series to arise

Question 8

allele frequency

Answer 8

the proportion of all copies of a gene in a population that are a given allele type (percentage of the total number of gene copies)

Question 9

wild-type frequency

Answer 9

most common alleles in a population; present in a population at a frequency greater than 1%

Question 10

mutant allele

Answer 10

a rare allele in the same population

Question 11

monomorphic

Answer 11

a gene with only one common wild-type alleles

Question 12

polymorphic

Answer 12

some genes have more than one common allele

Question 13

common variants

Answer 13

high frequency alleles

Question 14

pleiotropy

Answer 14

phenomenon where a single gene can determine a number of distinct and seemingly unrelated characteristics

Question 15

viable

Answer 15

likelihood of survivable

Question 16

recessive lethal allele

Answer 16

an allele that negatively effects the survival of a homozygote

Question 17

delayed lethality

Answer 17

homozygotes may survive beyond birth and die later from the deleterious consequences of the genetic defect

Question 18

complementary gene action

Answer 18

genes working together to produce a particular trait

Question 19

epistasis

Answer 19

a gene interaction in which the effects of an allele at one gene hides/masks the effects of alleles at another gene

Question 20

epistatic

Answer 20

allele that is doing the masking

Question 21

hypostatic

Answer 21

allele being masked

Question 22

recessive epistasis

Answer 22

when homozygosity for a recessive allele of the second gene is required to hide the effects of another gene

Question 23

dominant epistasis

Answer 23

epistasis in which the dominant allele of one gene hides the effects of another gene

Question 24

redundant gene action

Answer 24

genes act randomly when dominant, functional alleles of either one or the other is required in a pathway

Question 25

heterogeneous trait

Answer 25

a mutation at any one of a number of genes that can give rise to the same phenotype

Question 26

complementation test

Answer 26

method of discovering whether a particular phenotype arises from mutations in the same or separate genes

Question 27

complementation

Answer 27

occurs when the parents are affects by the gene but the offspring is not

Question 28

penetrance

Answer 28

how many members of a population with a particular genotype shows the expected phenotype

Question 29

expressivity

Answer 29

the degree or intensity with which a particular genotype is expressed in a phenotype

Question 30

modifier genes

Answer 30

have a subtle, secondary effects on traits

Question 31

conditional lethal

Answer 31

lethal only under certain conditions

Question 32

temperatures which the organisms remain viable

Answer 32

permissive conditions

Question 33

restrictive conditions

Answer 33

lethal conditions above permissive conditions

Question 34

phenocopy

Answer 34

a change in phenotype that does not result from a change in a gene