Chapter 3.2: Extensions to Mendel for Multifactorial Inheritance

Question 1

Define permissive conditions

Answer 1

range of temperature organism remains viable

Question 2

Continuous traits are usually __genic?

Answer 2

polygenic

Question 3

Define pentrance

Answer 3

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

Question 4

What is redundant gene action?

Answer 4

 Redundant gene action is when proteins encoded by the dominant alleles function in parallel, redundant pathways

Question 5

Define phenocopy

Answer 5

a change in phenotype due to chemical/environmental agent exposure

Question 6

What is complementary gene action?

Answer 6

 Complementary gene action is when two genes work together to produce a trait and the dominant allele of each gene must be present

Question 7

What are factors that alter the phenotypic expression of genotype? (3)

Answer 7

o Factors that alter the phenotypic expression of genotype include modifier genes, the environment, and chance

Question 8

What are continuous traits also called?

Answer 8

qualitative traits

Question 9

Define restrictive conditions

Answer 9

lethal temperatures organism is unviable

Question 10

What does dominant epistasis often indicate?

Answer 10

• Dominant epistasis often indicates that alleles of the two genes have antagonistic functions

Question 11

What is range of temperature organism remains viable?

Answer 11

permissive conditions

Question 12

What is the presence or absence of the dominant alleles of two genes?

Answer 12

genotype class

Question 13

What is lethal temperatures organism is unviable?

Answer 13

restrictive conditions

Question 14

What are continuous traits?

Answer 14

o Continuous traits (also called qualitative traits) vary over a range of values and can usually be measured

Question 15

What is a complementation test?

Answer 15

 The method of discovering whether a particular phenotype arises from mutations in the same or separate genes is a naturally occurring version of an experimental genetic tool called the complementation test

Question 16

What are modifier genes?

Answer 16

 Modifier genes alter phenotypes produced by the alleles of other genes

Question 17

Define heterogeneous trait

Answer 17

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

Question 18

Define epistasis

Answer 18

a gene interaction in which the effects of an allele at one gene hide the effects of alleles at another gene

Question 19

What is the degree of intensity with which a particular genotype is expressed in a phenotype?

Answer 19

expressivity

Question 20

Define polygenic

Answer 20

controlled by multiple genes

Question 21

Define conditional lethal

Answer 21

allele is lethal only under certain conditions

Question 22

What is a gene interaction in which the effects of an allele at one gene hide the effects of alleles at another gene?

Answer 22

epistasis

Question 23

What is an allele is lethal only under certain conditions?

Answer 23

conditional lethal

Question 24

What is dominant epistasis?

Answer 24

 Epistasis in which the dominant allele of one gene hides the effects of another gene is called dominant epistasis

Question 25

What is epistatic?

Answer 25

 The allele that is doing the masking is epistatic to the gene that is being masked

Question 26

What is controlled by multiple genes?

Answer 26

polygenic

Question 27

Define genotype class

Answer 27

the presence or absence of the dominant alleles of two genes

Question 28

What is recessive epistasis?

Answer 28

 Recessive epistasis is when the allele causing the epistasis is recessive

Question 29

Why do Humans require pedigree analysis instead of breeding experiments to determine how a trait is inherited?

Answer 29

o Breeding experiments cannot be done for ethical reasons

Question 30

Define expressivity

Answer 30

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

Question 31

What is how many members of a population with a particular genotype showed the expected phenotype?

Answer 31

penetrance

Question 32

The majority of traits are what? (gene number)

Answer 32

multifactorial

Question 33

What is a change in phenotype due to chemical/environmental agent exposure?

Answer 33

phenocopy

Question 34

What is a mutation at anyone of a number of genes that can give rise to the same phenotype?

Answer 34

heterogeneous trait

Question 35

What do the phenotypic ratios resulting from dominant epistasis depend on?

Answer 35

• The phenotypic ratios resulting from dominant epistasis depend on the specific functions of the different alleles and the particular biochemical pathways in which the genes participate

Question 36

What type of proteins do redundant genes often specify?

Answer 36

• Often, redundant genes specify nearly identical proteins that perform the same function