Past test questions Flashcards
DNA
- is composed of 2 parallel chains bound together by strong sugar phosphate bonds
- is a polymer of nucleotide unites bound together, end to end by weak hydrogen bonds
- replicated 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
- mRNA carries the genetic information from DNA
- Is involved in both transcription and translation
Gene Linkage
- condition where allelic gene pairs consistently travel together through meiosis and syngamy
- crossing over involved the reciprocal exchange of chromosomes segments between homologs and may disrupt the linkage of two genes
- 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 includes
- addition of a 7-methyl guanosine cap
- Addition of poly-A tail to a primary transcript
- splicing of introns
In the hardy-weinberg equation, the term 2pq represents the frequency of the
-heterozygous
AaBb x aabb is an illustration of a
- dihybrid cross
- test cross
Benefits of alternative splicing includes
-generated different proteins from single gene
Stop codons included the following except
-UAU
The inheritance of scurs (small, moveable horn-like growths in cattle) is dominant in males and recessive in females
sex-influenced
Parents with normal vision (not color blind) produce daughters that have normal vision, but if the dam is a carrier, half of the sons will be color blind
sex-linked
An allele in horses gives rise to the overo-coat color pattern, which involves white primarily on ventral surfaces of the horse. Homozygosity for the overo allele result sin all white foals that suffer from aganginosis of the large intestine and die within a few days of birth
lethal
The three consecutive bases on the mRNA is a codon that specifies an amino acid. There are 64 codons in total and they code for the 20 amino acids?
genetic code
A situation where heterozygotes is superior to both homozygotes in performance or disease resistance?
overdominance
Xeoderma Pigmentosum in humans is controlled by a single autosomal gene. DD individuals are normal, Dd individuals have freckled skin, and dd individuals have freckled (especially the face) that ulcerates when exposed to UV light. The result is cancer of 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 autosomes and can only be expressed in one sex due to anatomical differences and have to penetrance or simple turned off in the other sex?
sex-limited
A relatively common form of congenital heart disease, conotruncal septum defecrs, found in keeshounds and can be divided into four different grades of increasing severity?
variable expersivity
Group of individuals within a species which potentially can interbreed and share a common gene pool?
population
If a strong negative change in mature weight is observed along with a strong postive change in meat tenderness then the two traits have a
-weak positive correlation
Which of the following is considered the most important genetic parameter for an individual?
breeding value
The degree of homozygosity in the offspring can be affected by
- genetic relationship of the parents
- the heritability value of the traits
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
-A and B only
(-expected proportion of homozygous and heterozygous individual deviates from HW)
(-Assignment of mate can be based on genetic relationship and phenotypic similarity)
Inbreeding depression
- oppostite of heterosis
- results from poor gene combination value
Byx
- 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 depend on
- genetic relationships of the parents
- traits heritability
The following are examples of a major or extensive use of crossbreeding except
-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
-A and C only
(-results from increased heterozygosity)
(-gene combinations are not transmitted to the progeny)
Assume the average bird weight in a population is 75 lbs, the average weaning weight in a population is 400 lbs, and the phenotypic regression of weaning weight on birth weight is 2.75 lb per pb. If a calf’s birth weight is 77 lbs, then what is the estimated weaning weight for this cald?
404.4 lbs
The measure of stength between breeding value for one trait and breeding value for another trait?
genotypic correlation
The measure of how well two breeds complement 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 same alleles and 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
Mating purebred males to non-purebred females in an attempt to create a purebred population?
topcrossing
Combining the desirable characteristics of 2 or more breed (or lines) into the same offspring?
breed complementation
Animal model which combines all information known about an individual and it’s 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 outbred mating in comparison to the average phenotypic merit of offspring from purebred mating contributing to the cross?
heterosis
Term used for alleles in individuals that happen to look alike but not traceable to a common ancestor?
alike in state
The ability of the parent to impress its hereditary characters on its progeny because of increased homozygosity?
prepotency
The probability that 2 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 individual performance
- based on individual record
- the higher the heritability, the greater the accuracy
- the accuracy is equal to square root of heritability
Pedigree information is one of the valuable sources of 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
- animals must meet standard for each trait in order to be saved for breeding purposes
- it has a potential of culling animal that is outstanding for 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 equations using matrix algebra
Across breed EPD adjustments
- used 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 the 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 bulls
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 animal’s 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 environment?
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 breeding value 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 severe lethal deformities in calves (rear legs with fused joints, large abdominal hernias, skull deformity)?
tibial hemimelia
In the equine selection, taking the fastest winning times at a particular distance for the past 3 years at a given time?
speed index
An inherited disease in horses caused by a defect in voltage gated sodium channels of muscle cells?
Hyperkalemic Periodic Paralysis
A condition where foals can’t efficiently store and metabolize glucose which leads to abnormal polysaccharides in cells?
Glycogen Branching Enzyme Deficiency
An important trait of economic importance in sheep which related live weight to carcass weight?
dressing percentage
The systematic collection of comparative production information on an individual?
performance testing
The selection differential measured in phenotypic standard deviation units of the selected trait. It is inversely proportional to the proportion of the available replacements actually selected to be parents of the next generation?
selection intensity
A recorded trait that has been standardized for a given effect such as age or for environmental factors?
adjusted trait
A collection of information that has been systematically organized for easy access and analysis?
database
Refers to the ability of a breeding animal to remain in the breeding herd?
stayability
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 Mycloencephalopathy
An inherited disease in Dairy where animals have recurring soft tissues, fever, low appetite, chronic pneumonia, and diarrhea?
BLAD
