exam 2 Flashcards
the study of inheritance
genetics
rodlike bodies contained within the nucleus of a cell
chromosome
functional units of inheritance
genes
location of gene in a chromosome
locus
corresponding in type of structure and derived from a common primitive origin
homologous
designating an individual that possesses unlike genes for a particular trait
heterozygous
any observable or measurable characteristic of an individual
trait
an observed category or measured level of performance for a trait of an individual
phenotype
allele with the greater effect is dominant over its recessive counterpart
dominant vs. recessive
increase in productivity in crossbred progeny above the average of the breeds that were crossed
heterosis
hybrid vigor =
heterosis
mating of animals more closely related than the average population
inbreeding
mating of animals not as closely related as the average of the population
outbreeding
quickly identifies desirable and undesirable genes
inbreeding
mild form of inbreeding, used to maintain a high genetic relationship to an outstanding ancestor
line breeding
crossing so the strengths of the breeds compliment one another
heterosis
subjectively measured
qualitative
objectively measured
quantitative
all the elements of the genetic model for quantitative traits applied to the individual as opposed to a population
value
result of both the cumulative effects of the individual genes and the effect of gene combinations
genotype
expression of a given trait
phenotype
summation of all non-genetic influences
environment
total of all the independent genetic effects in an animal on a given trait
breeding value
portion of the genotype attributed to the gene combinations unique to particular animal
non-additive value
true or false: non-additive values are passed on to the next generation
false
superiority of selected animals compared to herd average
selection differential
portion of the selection differential that is passed from parent to offspring
heritability
high heritable traits
40%+
medium heritability
20-39%
low heritability
<20%
genetic change/year
heritability x selection differential generation interval
average age of parents when offspring are born
generation interval
basis for selection
pedigree, individual performance/appearance, progeny testing
EPD
Expected progeny differences
EPD’s are calculated for traits by utilizing information on
individual, siblings, ancestors, progeny
pure breds with recorded pedigree
seedstock producers
cross two or more breeds or lines of breeding
commercial producers
knowing which genes 2 animals have in common and if they exist in homo or hetero
relationship
inbreeding increases ….
homozygosity
in inbreeding 60-70% of herds show …
detrimental effects
in inbreeding 30-40% show…
no detrimental effects
inbred animals with superior performance are most likely to have …..
superior breeding value
crossbreeding is used for
complementation of breeds and heterosis
increase in productivity in the progeny above the average line that are crossed
heterosis
unrelated animals within the same breed are mated which increases heterozygosity
outcrossing
outcrossing is usefulness is ….
dependent upon selection
the ovary produces
ova (eggs), estrogen, and progesterone
site of fertilization
oviducts