Chap 4 - Inheritance Patterns Of Single Genes

Front 1

Dominant Gene - def'n

Back 1

A gene seen in organisms with the homozygous and heterozygous genotypes

Front 2

Recessive Gene - def'n

Back 2

A gene seen in organisms with the homozygous genotype only

Front 3

Haplosuffient - def'n

Back 3

One copy of a gene is sufficient to produce the wild-type phenotype in the heterozygous genotype

Front 4

Haploinsuffient - def'n

Back 4

A single copy of a gene is not sufficient to produce the wild-type phenotype in the heterozygous genotype

Front 5

Loss of Function Mutation

Back 5

Results in a significant decrease or in the complete loss of the functional activity of a gene product

Front 6

Gain of Function Mutation

Back 6

Identification of alleles that have acquired a new function of have their expression altered in a way that gives them substantially more activity that the wild-type allele

Front 7

Null/Amorphic Mutation - def'n

Back 7

A loss-of-function mutation that results in a complete loss of gene function in comparison to the wild-type gene product.

The mutant alleles produce no functional gene product and are often lethal in a homozygous genotype

Front 8

Leaky/Hypomorphic Mutation

Back 8

A mutation resulting in partial loss of gene function .

Often recessive and lethal.

Front 9

Hypermorphic Mutation

Back 9

Mutation that produces more gene activity per allele than the wild-type.

Usually Dominant

Front 10

Neomorphic Mutation

Back 10

Gain-of-function mutation resulting in novel gene activity not found in the wild-type

Front 11

Incomplete (Partial) Dominance

Back 11

The phenotype of the heterozygote is intermediate between the phenotypes of the homozygous organisms

Front 12

Codominance

Back 12

The equal and detectable expression of both alleles in heterozygotes

Front 13

Allelic Series - def'n

Back 13

An order of dominance among alleles, based on the activity of each allele's protein product.

Front 14

Allelic Series - e.g.

Back 14

Coat color determination in rabbits, where

C = wild-type

ch = Chinchilla

h = Himalayan

c = Albino

Allelic Series: C > ch > h > c

Front 15

Lethal Allele

Back 15

Single-gene mutation so detrimental that it causes death early in life or in gestation

Front 16

Sex-limited trait

Back 16

When both sexes carry a gene for a trait, but it is expressed in only one sex

Front 17

Sex-influenced Traits

Back 17

Traits in which the phenotype corresponding to a particular genotype differs depending on the sex of the organism

Front 18

Delayed age of onset

Back 18

Abnormalities manifest after the affected organism has had an opportunity to reproduce and transmit the mutation to the next generation

Front 19

Complete Penetrance

Back 19

Phenotype for a trait is always produced when the corresponding genotype is present

Front 20

Incomplete Penetrance

Back 20

A particular genotype does not always produce the corresponding phenotype

Front 21

Variable Expressivity

Back 21

One genotype produces phenotypes that vary in degree or form of expression

Front 22

Gene-Environment Interaction

Back 22

The result of the influence of environmental factors on the expression of genes and on the phenotypes of organisms

Front 23

Pleiotropy

Back 23

A single gene mutation that affects multiple and seemingly unconnected properties of an organism

Front 24

Gene Interaction

Back 24

The collaboration of multiple genes in the production of a single phenotypic character or a group of related characters

Front 25

Prototroph

Back 25

Wild-type

Front 26

Auxotroph

Back 26

Mutant, i.e. organism with mutations that prevents its growth on a minimal medium

Front 27

Epistatis

Back 27

Gene interactions in which an allele of one gene modifies or prevents the expression of alleles at another gene

Front 28

Hallmark of a Epistatic Interaction in a Dihybrid Cross

Back 28

A modification of the 9:3:3:1 ratio due to the combining of two or more genotype classes into a single phenotypic class

Front 29

Dominant Epistatis - ratio

Back 29

12:3:1

Front 30

Recessive Epistasis - ratio

Back 30

9:3:4

Front 31

Complementation Group

Back 31

Mutations of a single gene - i.e. many alleles - that do not complement one another

Front 32

Recessive Epistatis

Back 32

Phenotype produced by the interaction of two genes that control a trait in which alleles of one gene mask or reduce the expression of alleles of a second gene

Front 33

Nonpenetrant

Back 33

An organism with a genotype corresponding to a mutant phenotype that instead displays the wild-type phenotype

Front 34

Genetic Heterogeneity

Back 34

Same phenotype produced by mutation of any one of two or more different genes

Front 35

Temperature-sensitive Allele

Back 35

A mutation evident only at or above a certain temperature due to an abnormality of the protein product that affects its stability

Front 36

Genetic Complementation

Back 36

1. The observation of a wild-type phenotype in an organism or cell containing two different mutations

2. The cross of two pure-breeding mutants that yields progeny that are exclusively wild-type

Front 37

Dominant Epistatis

Back 37

Interaction of two genes that control a trait in which a dominant allele of one gene masks or reduces the expression of alleles of a second gene

Front 38

Penetrant

Back 38

Expression of the phenotype corresponding to a particular genotype