Exam 3 - Breeding And Biotechnology Flashcards
Molecular genetics
Structure and function of genes
Applied genetics
Improving genetic outcomes for the benefit of the animals and/or humans
Population genetics
Gene frequency within a population and how these frequencies influence genetics
Quantitative
Can be measured numerically, continuous variable
Qualitative
Can be described, expressed categorically, limited variables
Quantitative traits are controlled by ______ genes while qualitative traits are controlled by ______ genes
Many; few
Examples of quantitative
Milk yield, litter size, weaning weight, back fat thickness, eggs produced a year
Qualitative trait examples
Wool color, horns, white udders in cattle living outside, coat color
Heritability
The proportion of phenotypic variation that can be passed from parent to offspring
Quantitative traits: __________ environmental influence, _________ heritability
Qualitative traits: __________ environmental influence, _________ heritability
Quantitative: greater; variable
Qualitative: less; greater
Factors impacting genetic improvement of quantitative traits (3)
Heritability of trait, selection differential, generation interval
Heritability of the trait
May be used to estimate the value of an individual -its ability to transmit desirable genes to the offspring, can be used to predict the rate of genetic progress
Heritability
% of phenotypic variation among animals for a particular trait that is due to additive gene effects (not environment)
Greater heritability =
Greater improvement
Heritability range: 0-1
Highly heritable range:
Moderately heritable range:
Low heritability range:
Heritability range: 0-1
Highly heritable range: 0.4-0.6
Moderately heritable range: 0.2-0.4
Low heritability range: 0-0.2
Highly heritable range
0.4-0.6
Moderately heritable range
0.2-0.4
Low heritability range
0-0.2
Selection differential
Phenotypic advantage of the animal chosen to be parents in relation to the average for the population
Superiority compared to the herd average for a particular trait
Genetic progress = _________ X ________
Selection differential X heritability
Generation interval
Average age of the parents at the birth of their first offspring that in their turn will produce the next generation of breeding animals
How long it takes to pass along genetics
How to calculate generation interval
(Average age of breeding females + average age of breeding males)
/2
Limiting factor to generation interval
Breeding age of female
Genetic change per year (annual rate of genetic progress) =
(Heritability X selection differential) / generation interval
_______ and _______ are tools used to make genetic changes in a herd
Selection and mating
Random mating
Selected animals mate at random (each male has opportunity to mate with each female)
In-breeding
Intensive breeding of close relatives practiced to maintain breed standards and increases predictability of offspring because limited gene pool
Inbreeding depression
After generations dominant traits can lose their vigor and have reduced survival and fertility of offspring of related individuals
Challenges with in-breeding
Increased homozygosity, greater chance that detrimental genes will be expressed, decreased fitness/performance, inbreeding depression
Line-breeding
Less restrictive than in-breeding, maintain high genetic relationship to a superior ancestor, useful when producer has difficulty finding superior genetics outside own herd
Out-breeding
Mating of unrelated animals within lines and breeds or between breed
Out-breeding has __________ effects in lowly heritable traits and within the _______ generation of crossbreeding
Greatest; first
Outcrossing
Individual lines unrelated for at least 4-6 generations
Crossbreeding
Mating animals of different breeds for breed complementation, utilize different breeds with strength in traits of interest
Inbreeding: _______ variation _______ homozygosity
Outbreeding: _______ variation _______ heterozygosity ________productivity through hybrid vigor
Inbreeding: decrease; increase
Outbreeding: increase; increase; increase
Heterosis/Hybrid vigor
Increased productivity of crossbred progeny above average of breeds or lines that are crossed
Why chose hybrid vigor
Fewer unfavorable recessive genes expressed, favorable dominant genes are combined
Hardy-Weinberg Equilibrium
In a large, randomly mated population, the absence of any evolutionary forces, gene frequencies will remain constant
Does not usually happen in domesticated animal population
Molecular genetics
Branch of genetic dealing with the structure and activity of genetic material at the molecular level
Transgenic organisms
Purposeful manipulation of an organisms DNA to produce organisms with genomes that cannot be created through traditional breeding
Transgenic organism examples
Production of pharmaceuticals, study of human disease, direct benefit to the animal (disease resistant), development of animal used to harvest organ transplant, protecting the environment
Cloning
Process of producing a genetic copy of a DNA segment, gene, embryo or animal
Types of cloning (3)
DNA cloning, reproductive cloning, therapeutic cloning (embryo cloning)
DNA cloning
Generate multiple, identical, copies of DNA
Reproductive cloning
Harvesting a cell from an animal and then transplanting the nucleus from that cell into an egg that has had the nucleus removed
Therapeutic cloning (aka embryo cloning)
Production of embryos for use in research, with the goal of harvesting stem cells rather than creating cloned animals
