Prior Exam Material Flashcards
Similar chromosomes carrying the same types of genes…
homologous chromosomes
Individual with a matched pair of alleles…
homozygous
Have only one member of each pair of chromosomes, therefore called a haploid…
gametes
sperm
egg
Traits such as a scrotal circumference or milk production are examples of…
sex-limited traits
The fundamental unit of inheritance…
gene
Gametogenesis as it occurs in females is termed…
oogenesis
An observed category or measured level of performance in an individual…
phenotype
A normal distribution does not…
accurately describe the distribution of threshold traits
What is influenced by one (or few) gene pairs and fit into phenotypic categories?
Qualitative traits
As animal breeders, we are concerned with the________ because it is what can be passed on to the next generation…
genotype
The two fundamental questions of Animal Breeders are 1) ___________ and 2) _____________
1) what is the best animal?
2) how do we breed animals so that their offspring will be better than their parents
What is the “big DNA crapshoot”?
if a dam and sire produce a superior offspring, there is no guarantee that they will produce an equal to it ever again
genetics are random
What does gametogenesis do to the gametes?
reduces the chromosomes in a sperm/egg to a haploid, then join to create the normal diploid in the zygote
What is the location of a gene on a chromosome called? What else is it referred to?
allele
the fundamental unit of inheritance
The testicles of a male and the ovaries of female produce gametes by a process called _________. The unique type of cell division in which gametes are formed is called ________.
gametogenesis
meiosis
Over-dominance means what?
heterozygotes possess MORE vigor than the homozygotes
When epistasis is occurring, we see…
interaction of genes at different locations
When sperm and egg unite, it establishes the…
paired condition of chromosomes in the zygote
A zygote is termed ______ because it contains chromosomes in pairs.
diploid
When a zygote is formed the genotype of an animal is…
permanently established
Regression is…
the amount of change expected in one variable for a given amount of change in another variable
A correlation coefficient is…
Correlation coefficients are confined to a range from _____.
a measure of the strength of the relationship between two variables in populations
-1.0 to 1.0
________ is a measure of how two traits (or values) vary together in a population
_______ is approximately the average deviation from the
mean
covariance
standard deviation
We collect samples of data from _______ to calculate sample statistics which are estimates of the _________.
populations
true population parameters
The sex chromosomes, X and Y, are not considered _______ as they have different _______ and lack corresponding genes
homologous
size and shape
Coat color inheritance in the Shorthorn breed serves as an example of how ____ gene action works. Mating a red Shorthorn bull with genotype RR to white Shorthorn cows with genotype rr would result in roan Shorthorn calves with genotype Rr
co-dominant
What can be passed from generation to generation?
the effect of individual genes
Genotype can be split into two components. The two components are…
additive (BV) and non-additive (GV)
What are the 4 parts of selection that improve polygenic traits?
challenging
long-term
cumulative
easier for carcass traits than reproductive traits
Measurement of strength between true genetic value and the predicted genetic value…
accuracy
The ability of an individual to produce progeny whose performance is especially like its own and its especially uniform is called…
prepotency
Matings within a breed across family lines (crossing unrelated families)…
outcrossing
When “analyzing the system” what 4 things are we looking at?
animals (genotype)
production environment
fixed resources and management
production inputs and marketing endpoint
What is the most challenging to change through selection?
improving growth rate
Heritability is…(3 things)
the relationship between phenotype and genotype
the proportion of phenotypic variance that can be explained by additive genetic variance
an indicator of how easily traits can be changed in response to selection
Polygenic traits are…(3 things)
traits influenced by many genes
typically more economic important
more challenging to select for than simply inherited traits
The process of deciding which animals will become parents…
replacement selection
What types of traits respond most favorably to cross-breeding? Example?
breeding values
a reproductive trait like age at puberty
Selection can be based on… (4 things)
phenotype (individual performance)
progeny testing
pedigrees
genetic prediction
The general goal for a breeding program or the idea of what constitutes the best animal
breeding objective
An observed category or measured level of performance for a trait in an individual
phenotype
With regard to the typical pyramid structure, information used to determine breeding objectives should be based on…(2)
information from end users
performance data indicating the genotypes with most profit potential relative to the marketing endpoint
Selection can be based on phenotype, progeny testing, pedigree, or genetic prediction. Of these four, _________ is the only one that accounts for each of the other three
genetic prediction accounts for the others
Phenotypes can be evaluated subjectively or objectively. There are ________ traits that can only be evaluated subjectively
economically important
An important responsibility of purebred seedstock breeders is to __________ in the _________ traits in their respective meat animal industry
make genetic improvements
economically important
The two fundamental questions of animal breeders are: 1) ______ and 2) _________
1) what is the best animal
2) how do you breed animals so that their offspring will be better than their parents
Relative to mating systems and industry structure, feedstock producers are more likely to ______ and commercial producers are more likely to ______
inbreed
crossbreed
It is possible to see ______ levels of heterosis (5-10%) in F1 crossbreds that still results in a ______ level of performance than one of the lines of purebred parents
high
lower
As animal breeders, we a primarily concerned with ________ of the individual
genetic makeup
The two basic tools used to improve animal populations are _____ and _______. _______ is the process of determining which males are mated to which females
selection
mating
mating
Traits that are low in heritability are influenced more by _______ and ______ genetic effects
environment
non-additive
________ traits are influenced by one gene pair (or a few) and typically qualitative
Simply inherited
Mating decisions are made to ______ the proportion of favorable _______ in future generations
increase
gene combinations
Crossbreeding=________=prepotency
heterozygosity
A crossbred is a hybrid but….
a hybrid is not always a crossbred
A race of animals within a species, usually with a common origin and similar identifying characteristics is called…
a breed
We need ______ to crossbreed and ______ to outcross
purebreds
inbreds
A _______ is a set of animals of the same sex, managed alike, close to the same age and given the same opportunity to perform in the same environment
contemporary group
_______ is an area of animal breeding concerned with the measurement of data, statistical procedures and computational techniques for predicted breeding values
Genetic prediction
In the typical pyramid structure of the meat animal industries, germ plasma flows ______ the pyramid and information should flow _____ the pyramid
down
up
With regard to proper breeding, objectives ______ is typically better. Seldom (if ever) is _______ the correct breeding objective
intermediate optimums
extremities (more is better, less is better)
The kind of animal that works best in one environment from will _____ from the optimal animal in different ______ scenarios
differ
production
Most breeding industries have a pyramid structure including relatively few _______ selling breeding stock to a larger number of _______ who sell breeding stock to a great number of ______ (commercial breeders)
elite breeders
multiplier breeders
end users
H=
2pq
P=
BV+GVC+E
can include mean
Selection for a higher Doc EPD would result…
more docile cattle
Selection for a higher HP EPD would result in….
increased probability of first pregnancy
EPDs are…
They are subject to change as more data is collected. More data results in higher accuracy and less possible change in EPD
an estimate of an animal’s true genetic value as a parent
Effective crossbreeding systems require _____ animals
purebred
BV represents the part of G that can be…
passed from parent to offspring
_______ is the sum of independent, additive gene effects that are transmissible to offspring
Breeding Value
Only one of each gene pair can be transmitted from parent to offspring
Genes cannot…
This explains why independent gene effects, but not __________, are transmitted from parents to offspring
can’t be transmitted in pairs
gene combination effects
The biological phenomenon called hybrid vigor is the result of…
non-additive genetic merit
________ effects can be temporary or permanent
Environmental
Independent gene effects are known as _______ since the BV for a trait is the sum of the independent gene effects over all loci
additive gene effects
Seedstock breeders sell not only animals but also….
The more and better the ________, the more valuable the product
information about these animals
information
EPDs cannot predict the…
As EPD is a prediction of how future offspring will perform for a specific trait in comparison to the offspring of another parent
level of performance of offspring
There is no “ideal” value of…
an EPD for any trait
$Values assign an _______ to several EPDs based on the traits financial importance to a specific selection goal or _______
economic weighting
marketing endpoint
What four things should be known about a trait before it is included in a selection program?
heritability
genetic correlation to other economically important traits
ease of measurement
economic importance
Discovering and identifying genetic defects is usually the result of…(4 things)
breeding to a common ancestor
breeding success
lethal and sub-lethal mutations
eliminating phenocopies as a potential cause
A Permanent Environmental Effect (like losing function in half the udder), would impact what in the lactating cow?
milk production in dairy cattle or any repeated trait
If you were looking at six locus genotypes, what combination would you expect to breed with the most prepotence?
Bbccddeeffgg
more homozygous means more prepotency
If a bull had a breeding value (BV) of 100 for Yearling Weight, what would be the bull’s progeny difference (PD) for Yearling Weight?
50
PD=.5*BV
If a population of Holstein cows has an average level of milk production of 20,000 lbs and one cow in the population has a G value of +1000 and an E value of -1000, what is her expected level of production?
20,000
P=mean+G+E
If a Holstein bull is mated to a large number of randomly selected dairy cows. On average, the female offspring resulting from the matings produced 225 lbs more milk per lactation than the average dairy cow. What is the sire’s progeny difference for milk production?
225
PD of sire will be same as number given. BV=2*PD
Polygenic, qualitative traits that follow a normal distribution but with regard to genetic prediction, we draw a point at which they exhibit the desired phenotype or if they fall below they exhibit the other phenotype. EPDs for these traits are often expressed as percentages
threshold traits
If N=normal development and n=lethal recessive gene which results in homozygous recessive genotypes being born dead. If Nn genotype have an advantage in fitness over NN genotypes, what impact would it have on the gene frequency of the n allele over time in this population?
gene frequency of n would increase
If one locus has two alleles A & a. Independent, additive effects on marbeling score are A=+1 and a=-1, furthermore A is completely dominant to a. What genotype should you select if your breeding objective is to increase marbeling?
using BV, AA (1+1)
You own an outstanding ewe flock and recently discovered they ALL are carriers of a lethal recessive gene. N is the allele that leads to normal development and n is the lethal recessive allele that results in the homozygous recessive genotype being born dead. You are currently in the process of selecting a new herd sire. What is the genotype you need in the next stud ram that will permit you to capture the genetic value of these breeding females while NEVER permitting the lethal recessive to manifest itself?
NN
Based on information in the Angus sire summary, what has one of the lowest heritabilities?
maternal milk
What is CED?
calving ease direct
unassisted births
What is BW?
birth weight EPD
sire’s ability to transmit birth weight
What is WW?
weaning weight
sire’s ability to transmit weaning weight to progeny
What is YW?
yearling weight EPD
sire’s ability to transmit yearling weight to progeny
What is RADG?
residual average daily gain
postweaning weight to progeny
What is DMI?
dry matter intake
feed intake during postweaning to progeny
What is YH?
yearling height
yearling height in inches to progeny
What is SC?
scrotal circumference
scrotal size in centimeters to progeny
What is Milk?
Maternal Milk EPD
milk and mothering ability from sire to progeny
What is HP?
heifer pregnancy
chance of first pregnancy from sire to progeny
What is CEM?
calving ease MATERNAL
unassisted births related to the daughter of the sires
What is MW?
mature weight EPD
mature weights of progeny from sires in lbs
What is MH?
mature height
difference in mature height of daughters from sires
What is Marb?
marbeling
What is RE?
ribeye area EPD
What is $V?
economic selection index compared to a value
What is EPD?
expected progeny difference
What is ACC?
accuracy or reliability of an EPD
What is Doc?
docility
What is Claw?
claw set EPD
relation to toes
What is Angle?
foot angle EPD
What is PAP?
pulmonary arterial pressure EPD?
What is CW?
carcass weight
What is Fat?
fat thickness
What is $M?
maternal weaned calf value
What is $W?
weaned calf value?
What is $F?
feedlot value
What is $G?
grid value
What is $B?
beef value
What is $C?
combined value
