final exam review Flashcards
if a strong negative change in mature weight is observed along with a strong positive change in meat tenderness then the two traits have a…
strong, negative correlation
what is considered the most important genetic parameter for an individual?
breeding value
the degree of heterosis in the offspring can be affected by…
- the repeatability value of the traits
- the type of gene action that the trait is under
correlation…
- the correlation of X and Y is the same as the correlation of Y and X
- correlation is unitless
- it only ranges from -1 to 1
in a non-random mating…
- expected proportion of homozygous and heterozygous individual deviates from H-W
- assignment of mate can be based on genetic relationship and phenotypic similarity
inbreeding depression…
- the opposite of heterosis
- results from poor gene combination value
bxy
- is the regression of Y on X
- variation in trait X influences the variation in trait Y
- there is an assumption of cause and effect
effects of outbreeding will include…
- increase in heterozygosity
examples of a major or extensive use of crossbreeding
- commercial cow/calf beef operation
- crossing of inbred lines to maximize production and growth in swine
- crossing of white cornish X white plymouth rock in poultry
not: crossing of two dairy breeds such as holstein and jersey
environmental correlation
- measure of strength of relationship between environmental effects of one trait and another
- they are often used for management purposes
heterosis
- results from increased heterozygosity
- gene combinations are not transmitted to the progeny
assume the average birth weight in a population is 75 lbs, the average weaning weight in a population is 400 lbs, and the phenotypic regression of weaning weight is 2.75 lb per lb. If a calf’s birth weight is 77 lbs, then what is the estimated weaning weight for this calf?
405.5 lbs
the measure of strength between BV for one trait and BV for another trait
genetic correlation
the measure of how well two breeds compliment each other for a specific trait
specific combining ability
a mating system where the best male for a trait is mated to the best female for that same trait
positive assortative mating
animals with the same alleles from a common ancestor are said to be…
identical by descent
a system of mating where genes of a common ancestor is concentrated in an individual
linebreeding
matching purebred males to non-purebred females in an attempt to create a purebred population
top crossing
combining the desirable characteristic of 2 or more breed (or lines) into the same offspring
breed complementation
animal model which combine all information known about an individual and its relative to create a genetic profile of the animal’s merit used mainly in meat producing animals
expected progeny difference
expectation of a squared deviation from its mean
variance
the superiority of the offspring from out red mating in comparison to the average phenotypic merit of offspring from purebred mating contributing to the cross
hybrid vigor
term used for alleles in individuals that happen to look alike but not traceable to a common ancestor
identical by state
the ability of the parent to impress its hereditary characteristics on its progeny because of increased homozygosity
prepotency
the probability that two alleles at a locus in an individual are identical by descent
inbreeding coefficient
rate of genetic change with selection will depend on:
- selection differential
- generation interval
- heritability
accuracy of an individual performance:
- based on individual record
- the higher the heritability, the greater the accuracy
- accuracy us equal to square root of heritability
pedigree information is one of the valuable sources for information for taking selection decision because:
- it is valuable for traits expressed later in life
- it is cheap
- it is valuable for sex-limited traits
the major objective for progeny testing for a qualitative trait:
to help determine the likelihood that an animal is a carrier of a detrimental recessive allele
independent culling method
- animal must meet standard for each trait in order to be saved for breeding purposes
- it has a potential of culling animal that is outstanding in one trait
BLUP
- method of genetic selection appropriate when performance data came from genetically diverse groups
- is an extension of selection index
- simultaneous solution of number of equation using matrix algebra
across breed EPD adjustments
- useful to commercial producers purchasing bulls for use in crossbreeding program
- accuracy of across breed EPD depends on accuracy of within-breed EPD for the bull
- useful in estimating divergence of birth weight EPD for bulls to breed to first calf heifers
in equine selection, some of the problems in determining heritability includes:
- tremendous environmental variation
- data bias
- limited information which results from analyzing the best
in dairy selection program, selection is primarily based on sire because:
- sire produces more progeny than dams
- AI allows for even larger number of progenies
- lower cost associated with keeping few or no bull at all
beef infrastructure includes the following:
- purebred
- cow/calf
- stocker
average age of parents when the animals that will replace them in the flock or herd are born
generation interval
a selection method that selects for a single trait at a given time
tandem selection
a measure of how good and close a calculated estimate of an animals genetic value is compared to the unknown true genetic value
accuracy
one of the markers associated with meat tenderness
calpastatin
a genetically similar group of animals born in a particular time period and raised under the same management and environmental conditions
contemporary group
changes in the ranking of performance of genotypes in different environments. For example, one genotype may perform the best in one environment and only average in another
genotype-environment interaction
the evaluation of an individual’s genotype using the performance records of its progeny
progeny test
the difference between the average for a trait in replacement animals and the average of the group from which the replacements were chosen
selection differential
a single number that predicts the BV of an individual for a weighted combination of traits
selection index
a developmental duplication in beef cattle with high embryonic death among homozygous recessive individuals with incomplete penetrance
polymelia
an autosomal recessive gene that is usually selected against in beef cattle production which is characterized by sever lethal deformities in calves
tibial hemmilia
linear descriptive traits that can affect milk production in dairy cows
type traits
an inherited disease in dairy where the animal shows bilateral hind leg weakness between ages 6-18 months resulting in a weaving gait
bovine progressive degenerative myloencephalopathy
an inherited disease in dairy where animals have recurring soft tissues, fever, low appetite, chronic pneumonia and diarrhea
BLAD
in equine selection, taking the fasted wining times at a particular distance for the past 3 years at a given track
speed index
an inherited disease in horses caused by a defect in voltage-gated sodium channels of muscle
hyperkalemic periodic paralysis
a condition where foals can’t efficiently store and metabolize glucose which leads to abnormal polysaccharides in cells
GBED
an important trait of economic importance in sheep which relates live weight to carcass weight
dressing percent
the systematic collection of comparative production information on an individual
performance testing
refers to the ability of a breeding animal to remain in the breeding herd
stayability
a collection of information that has been systematically organized for easy access
database
a recorded trait that has been standardized for a given effect such as age or environmental factors
adjusted trait
the selection differential measured in phenotypic standard deviation units of the selected trait. It is inversely proportional to the proportion of available replacements actually selected to be the parents of the next gen
selection intensity
DNA…
- is a polymer of nucleotide units bound together, end to end by weak hydrogen bonds
- replicates prior to cell division during mitosis
meiosis…
- meiosis II consists of division of haploid cells
- in the male, the result is 4 functional sperm cells
RNA…
- codes for DNA
- tRNA is used as a template for protein synthesis
gene linkage…
- the probability of recombination of genes by only two loci depends on the distance btwn homologous chromosomes
- recombination involves new allelic pairings of genes
Hardy Weinberg…
- is an equilibrium law dealing with large random mating populations
- is a mathematical formula that describes genotypic frequencies in terms of phenotypes
post-transcriptional RNA modifications include:
- addition of 7 methylguanosine cap
- addition of a poly-a tail to a primary transcript
- splicing of introns
in the hardy-weinberg equation, 2pq represents the frequency of the…
heterozygotes
AaBb x aabb is an illustration of a…
dihybrid cross
benefits of alternative splicing includes…
- decrease the chance for exon shuffling through recombination
- generates different proteins from single gene
stop codons include all of the following except…
- UAA
- UAU
- UGA
- UAG
- UAU
incurrence of scours (small, moveable, horn-like growths of cattle) is dominant in males and recessive in females
sex-influenced traits
parents with normal vision produce daughters that have normal vision, but if the dam is a carrier, half of the sons will be color blind
x-linked trait
an allele in horses gives rise to the overdo coat color pattern, which involves white primarily on ventral surfaces of the horse. Homozygousity for the overdo allele results in all while foals that suffer from a ganglion oasis of the large intestine and die within a dew days of birth
lethal genotype
the three consecutive bases on the mRNA is a codon that specifies for a specific amino acid. There are 64 codons in total and they code for the 20 amino acids.
genetic code
a situation where heterozygosity is superior to both homozygotes in performance and disease resistance
overdominance
xeroderma pigmentosum in humans is controlled by a single autosomal gene. DD individuals are normal, Dd have freckled skin and did habe freckled skin that ulcerates when exposed to UV light. the result is cancer in these areas which is fatal to these individuals before reproductive age.
semi-lethal
the phenotypic effect of a gene at one locus is dependent on what allele is present at another locus
epistasis
traits that are governed by genes on the autosome s and can only be expressed in one sex due to anatomical differences and have no penetrance or simply turned off in the other sex
sex-limited trait
a common form of congenital heart disease, conotruncal septum defects, is found in keeshounds and can be divided into four different grades of increasing severity
variable expressivity
group of individuals within a specie which potentially can interbreed and share a common gene pool
population
observable characteristic
phenotype
alternate forms of a gene
alleles
alleles of one gene separate into gametes randomly with respect to other genes
independent assortment
reproductive cells containing only one copy of each gene
gametes
the heritable entity that determines a characteristic
gene
the separation of the two alleles of a gene into different gametes
segregation
an individual with two different alleles of the same gene
heterozygote
the allele expressed in the phenotype of the heterozygote
dominant
offspring of the P generation
F1
having two identical alleles of a given gene
homozygote
a cross between individuals both homozygous for two genes
dihybrid cross
the allele that doesn;t contribute to the phenotype of the heterozygote
recessive
the cross of an individual of ambiguous genotype with a homozygous recessive individual
test cross
the alleles an individual has
genotype
proportion of individuals carrying a particular variant of a gene that also express an associated phenotype
penetrance
the description of how an animal should look and behave
breed standards
