Exam 1 Flashcards

1
Q

What is a trait?

A

An observable or measurable characteristic of an individual

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2
Q

What is an example of observable traits?

A

Appearance (coat color, horned, frame size)

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3
Q

What is an example of measurable traits?

A

Performance (weaning weight, yearling weight, scrotal circumference, milk yield, yield grade, quality grade)

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4
Q

What is phenotype?

A

Observed category or measure of performance for a trait of an individual

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5
Q

What are 2 examples of the difference between a trait and phenotype?

A

Phenotype: red Trait: coat color
Phenotype: 565 lbs Trait: weaning weight

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6
Q

What is genotype?

A

Genetic makeup of an individual

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7
Q

What do the letters in P=G+E mean?

A

Phenotype
Genotype
Environment

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8
Q

What is biological type?

A

Similar genotypes for traits of interest

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9
Q

When choosing the best animal, what makes up the system?

A

Genotype
Physical environment
Fixed resources and management
Economics

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10
Q

What are interactions?

A

A relationship where the effects of one component depends on another component

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11
Q

What is genotype by environment?

A

Different in performance between 2 or more genotype changes from environment to environment

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12
Q

In order to look at a G x E interaction, what must there be?

A

At least 2 genotypes and 2 environments

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13
Q

When looking at a graph, how do you know if there was an interaction?

A

If there was a swap in rank or change in magnitude

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14
Q

What are breeds?

A

Race of animals within species that have a common origin and similar characteristics

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15
Q

What are 4 examples of breeding objectives?

A

Carcass characteristics
Replacement females
Milk quality
Wool production

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16
Q

What is a population?

A

Group of intermating individuals

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17
Q

What are the 2 types of selection?

A

Natural

Artificial

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18
Q

What is natural selection?

A

Survival of the fittest

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19
Q

What is natural selection independent of?

A

Humans

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20
Q

What is an example of natural selection?

A

Hyperkalemic periodic paralysis

Parasite resistance

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21
Q

What is artificial selection?

A

Human control

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22
Q

What are some examples of artificial selection

A

Replacement

Culling

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23
Q

How is phenotypic selection done?

A

Through performance

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24
Q

How do we select the best breeding value? (4)

A

Measure performance
Information on relatives
Progeny
Genetic predictions

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25
Q

What is breeding value?

A

Value of the animal genetically and how it contributes in breeding

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26
Q

What are polygenic traits?

A

Traits made of many genes

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27
Q

What are simply-inherited traits?

A

Traits made of few genes

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28
Q

What are different matings and mating systems? (4)

A

Complementarity
Hybrid vigor/heterosis
Related individuals
Corrective matings

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29
Q

What is complementarity considered to be?

A

The best of both worlds

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30
Q

What are examples hybrid vigor/heterosis? (3)

A

Lines
Breeds
Species

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31
Q

What are examples of why you would use corrective matings? (2)

A

Frame size

Structure

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32
Q

How are quantitative traits measured?

A

By a bell curve

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33
Q

What are quantitative traits affected by?

A

Many genes

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34
Q

What is population mean denoted by?

A

μ

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35
Q

What is the sample mean?

A

Sum of all observations divided by sample size

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36
Q

What is variation?

A

How individuals vary for a particular trait in a population

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37
Q

What do variations in breeding values allow for?

A

Selection

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38
Q

What is variation described by?

A

Variance

σ^2

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39
Q

What is standard deviation?

A

The average deviation from the mean

σ

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40
Q

What percentage of the population does 1 standard deviation account for? 2? 3?

A

68%
95%
99%

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41
Q

Write the formula for variance. Check notes for answer equation 2

A

Write the formula for variance. Check notes for answer equation 2

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42
Q

How do you calculate standard deviation?

A

Square root of variance

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43
Q

What is covariation?

A

How 2 traits vary together

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44
Q

What are the 3 aspects of covariation?

A

Direction
Correlation
Regression

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45
Q

What are the 3 types of direction?

A

Positive covariation
Negative covariation
No covariation

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46
Q

What is positive covariation?

A

Positive deviations with positive deviations

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47
Q

What is negative covariation?

A

Positive deviations with negative deviations

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48
Q

What is zero covariation?

A

No pattern

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49
Q

Write the formula for covariance. Check notes for answer equation 3

A

Write the formula for covariance. Check notes for answer equation 3

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50
Q

What is correlation?

A

Strength of the relationship between 2 variables

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51
Q

What is the variable for correlation coefficient?

A

r_x,y

52
Q

What are the 3 types of correlations?

A

Phenotypic correlations
Genetic correlations
Environmental correlations

53
Q

Write the formula for correlation coefficients. Check notes for answer equation 4

A

Write the formula for correlation coefficients. Check notes for answer equation 4

54
Q

How is the correlation coefficient interpreted?

A

There is a (weak, moderate, strong: positive, negative) correlation between variable x and variable y

55
Q

What is regression?

A

The amount of change in a variable that can be expected for a given amount of change in another variable

56
Q

What is the variable for regression coefficient?

A

b_y,x

57
Q

Is b_y,x the same thing as b_x,y?

A

No

58
Q

In the regression coefficient is y the dependent or independent variable? X?

A

Dependent

Independent

59
Q

How is the regression coefficient interpreted?

A

If x moves 1 unit, y moves _____ on average

60
Q

Write the formula for regression coefficient. Check notes for answer equation 5

A

Write the formula for regression coefficient. Check notes for answer equation 5

61
Q

What is the model for quantitative traits?

A

P = μ + BV + GCV+ E

62
Q

Write down the formula for prediction. Check notes for answer equation 7

A

Write down the formula for prediction. Check notes for answer equation 7

63
Q

How can you determine possible genotypes and phenotypes? (3)

A

Punnett square
Genotypic ratio
Phenotypic ratio

64
Q

How do you calculate the number of possible gametes?

A

2^n where n is the number of loci that are heterozygous

65
Q

How do you calculate the number of zygotes?

A

3^n x 2^m where n is the number of loci where both are heterozygous and m is the number of loci where only one parent is heterozygous

66
Q

What are the different types dominance? (4)

A

Complete dominance
Partial dominance
Over dominance
No dominance

67
Q

What is complete dominance?

A

When the heterozygote is the same as homozygous dominant

68
Q

Draw complete dominance graph

A

Draw complete dominance graph

69
Q

What is partial dominance?

A

When the heterozygote is intermediate to homozygous genotypes, but more closely resembles the dominant

70
Q

Draw partial dominance graph

A

Draw partial dominance graph

71
Q

What is over dominance?

A

When the heterozygote is outside of the range homozygous genotypes, but closely resembles dominant

72
Q

Draw over dominance graph

A

Draw over dominance graph

73
Q

What is no dominance?

A

When the heterozygote is midway between the homozygous genotypes

74
Q

Draw no dominance graph

A

Draw no dominance graph

75
Q

What is epistasis?

A

Interaction among genes at different loci

76
Q

What is an example of epistasis?

A

Golden retriever

77
Q

What are 3 types of sex-related inheritance?

A

Sex-linked
Sex-limited
Sex-influenced

78
Q

What is sex-linked?

A

Inheritance located on sex chromosomes

79
Q

What is sex-limited?

A

Phenotypic expression is limited, such as milk production–both carry the gene, but female expresses

80
Q

What is sex-influenced?

A

Expression differs between male and females

81
Q

What is gene or allelic frequency?

A

Frequency of a gene in a population

82
Q

What is the equation for gene/allelic frequency?

A

p + q = 1

83
Q

What is genotypic frequency?

A

Frequency of a particular one-locus in a population

84
Q

What is the equation for genotypic frequency?

A

P + H + Q = 1

85
Q

How can genotypic frequencies be changed?

A

Increase the frequency of favorable genes

86
Q

What is the effect of inbreeding mating systems?

A

Increase homozygosity, decrease heterozygosity

87
Q

What is the effect of outbreeding mating systems?

A

Increase heterozygosity, decrease homozygosity

88
Q

How do you calculate new gene frequencies with genotypic frequencies?

A
p = P + 1/2(H)
q = Q + 1/2(H)
89
Q

What is the Hardy-Weinburg Equilibrium?

A

In a large, random mating, population gene and genotypic frequencies remain constant from generation to generation in absence of selection, mutation, and migration

90
Q

What is the formula for Hardy-Weinburg Equilibrium?

A

p^2 + 2pq + q^2

91
Q

What are characteristics of simply inherited traits?

A

Either/or, categorical, quantitative

Affected very little by environment

92
Q

What are characteristics of polygenic traits?

A

All genes add together to produce performance
Quantitative, continuous
Affected by environment

93
Q

What are threshold traits?

A

Polygenic traits that exhibit categorical phenotypes such as dystocia and fertility

94
Q

What are the 2 different breeding approaches?

A

Simple

Polygenic

95
Q

What is the simple breeding approach like? (3)

A

Easy to identify genotypes
Effects of specific genes
Identify through test mating or test cross

96
Q

What is the polygenic breeding approach like? (5)

A
More genes affecting a trait
More difficult to observe individual gene effects
Less info about those genes
Difficult to identify animal's genotype
Evaluate net effect
97
Q

What is a one-locus case?

A

Selecting for particular phenotypes

98
Q

What do test matings reveal?

A

Genotype of an individual for a small number of loci

99
Q

What does the probability of an individual not being a carrier depend on?

A

What animals are being used for mating

How many times to mate

100
Q

What are 3 factors influencing effectiveness of selection?

A

Initial gene frequency
Fitness of gene in population
Degree of dominance

101
Q

If the initial gene frequency is high or low, what is the change like?

A

Slow

102
Q

If the initial gene frequency is medium, what is the change like?

A

Fast

103
Q

Where does the fastest change occur at in no dominance?

A

Intermediate gene frequency

104
Q

In complete dominance, what do you select against?

A

Dominant allele

105
Q

Why do we see do many recessive genes for the genetic defects despite strong natural and artificial selection against them?

A

Because there are carriers and we have no idea if it’s there unless we see it. The right mating must occur to see it

106
Q

With simply inherited traits, it’s it easy or hard to identify genotypes?

A

Easy

107
Q

With polygenic traits, it’s it easy or hard to identify genotypes?

A

Hard

108
Q

Since it is hard to identify genotypes with polygenic traits, how can use select animals?

A

Breeding value

109
Q

What is the basic model for quantitative traits represent by?

A

P = μ + BV + GCV + Ep + Et

110
Q

What is BV the sum of?

A

Independent gene effect of the animal’s genes for a particular trait

111
Q

How much of the genetic combination do parent’s transmit to one locus?

A

Half

112
Q

What part of the genotypic value can be transmitted from parent to offspring?

A

Breeding value

113
Q

How much of the breeding value is transmitted? What is this called?

A

Half

Progeny difference/transmitting ability

114
Q

What is the equation for progeny difference?

A

1/2 BV

115
Q

What is breeding value sometimes called?

A

Additive genetic value/additive value

116
Q

What is the BV of the offspring equal to?

A

1/2 BV sire and 1/2 BV dam

117
Q

What does the average performance of the offspring value equal?

A

μ + 1/2 BV sire + 1/2 BV dam

118
Q

What is genetic combination value?

A

Remaining portion of the value for a trait due to genetic combination effects (dominance and epistasis)

119
Q

Can GCV be transmitted from offspring to parent?

A

No

120
Q

What does genotypic value equal?

A

BV + GCV

121
Q

What are repeated traits?

A

Traits for which individuals commonly have more than one performance record

122
Q

What is producing ability?

A

Performance potential of an individual for a repeated trait

123
Q

What are permeant effects?

A

Affect of an individual performance for a repeated trait

124
Q

What are temporary traits?

A

Influence on a single performance record of an individual

125
Q

What is producing ability made of?

A

Ep, BV, and GCV