Gene Action

Question 1

Non additive

Answer 1

Qualitative traits (few genes)

Question 2

Dominant allele masks expression of recessive allele

Answer 2

Complete dominance

Question 3

Characteristics of both dominant and recessive alleles

Answer 3

Incomplete dominance

Question 4

Interaction between non allelic genes
3 types

Answer 4

Epistasis
1) complete dominance
2) recessive
3) incomplete

Question 5

Complete epistasis

Answer 5

Ex. Sheep wool pigment color determined by genes at another locus

Question 6

Recessive epistasis

Answer 6

B- black
bb- brown
C- melanin
cc- no melanin

Question 7

Incomplete

Answer 7

Horses
B- bay
bb- chestnut
CC- color
Cc- diluted
cc- no color

Question 8

Trait inheritance controlled by alleles on X chromosome

Answer 8

Sex linkage

Question 9

Autosomal genes

Answer 9

Non sex linked genes

Question 10

Which chromosome has more loci for sex linked traits?

Answer 10

X chromosome

Question 11

Sex linked trait example

Answer 11

Tortoiseshell cats
Mostly females
Piebald genes

Question 12

Human examples of sex linked traits

Answer 12

Muscular dystrophy
Hemophilia
Colorblindness

Question 13

Recessive sex linked

Answer 13

Only homozygous recessive are effected.
2 Heterozygous uneffected parents can produce 50% males with phenotype.

Question 14

Sex influenced

Answer 14

The trait inheritance is different in the 2 sexes despite having the same genotype.
Ex. Polled female sheep
Horned male sheep

Question 15

Sex limited

Answer 15

Expression of a trait that only occurs in one sex
Ex. Milk and egg production

Question 16

One gene influences multiple traits

Answer 16

Pleiotropy

Question 17

Phenotypic expression of a trait varies in those with the same genotype.

Answer 17

Veritable expressivity

Question 18

Alleles interact causing heterozygous to be superior to homozygous.

Answer 18

Overdominance

Question 19

Not all individuals with the genotype will display the phenotype

Answer 19

Incomplete penetrance
Ex. Polydactyl cats

Question 20

Lethal

Answer 20

Embryonic death or death shortly after birth
Ex. Homozygous dominant platinum foxes

Question 21

Death before puberty

Answer 21

Semi-lethal
More predictable

Question 22

Reduction in some measure of fitness or productivity

Answer 22

Detrimental
Ex. Comprest cattle

Question 23

2 non alleleic genes on the same chromosome. Tend to end up in same gamate

Answer 23

Linked genes

Question 24

Exception to gene linkage

Answer 24

Crossing over in mitosis
Crossing over can determine gene sequence on a chromosome

Question 25

Formation of a new gene combination as a result of crossing over.

Answer 25

Recombination

Question 26

Is crossing over more common in close genes or distant genes?

Answer 26

Distant genes

Question 27

Quantitative trait

Answer 27

Many genes involved in trait expression.
Trait expression has a range of values.
Ex. Milk production

Question 28

Proportion of genes expected to be passed from parent to offspring

Answer 28

Heritability

Question 29

What is heritability a measure of

Answer 29

Additive gene action

Question 30

Highly heritable trait

Answer 30

High performance parents= high performance offspring
Low performance parents= low performance offspring

Question 31

Not highly heritable trait

Answer 31

Parent’s performance has little effect on offspring’s performance

Question 32

Example of a trait that is not heritable even though it is genetically determines

Answer 32

Dog legs
All dogs have 4 legs
Dog leg length varied based on a heritable trait with variation.