Definition of common animal genetics/breeding terms Flashcards
— Adaptation traits contribute to individual fitness and to the evolution of
animal genetic resources
Adaptation traits
— The effect of an allele on animal performance, independent of the
effect of the other allele at a locus.
Additive genetic effects
— One of a pair, or series of alternative forms of a gene that can occur at a given locus
on homologous chromosomes.
Allele
— Any one of a class of organic compounds containing the amino (NH2) group and
the carboxyl (COOH) group. Amino acids are combined to form proteins.
Amino acids
— A system for genetic evaluations that estimates breeding values of individual
animals (males, females) at the same time. The system uses production data on all known
relatives in calculating a genetic evaluation
Animal model
— Any individual from which an animal is descended.
Ancestor
— Any chromosome that is not a sex chromosome
Autosome
— The cross produced by mating a first-cross animal back to one of its parent lines
or breeds
Backcross
— Either a sub-specific group of domestic livestock with definable and identifiable
external characteristics that enable it to be separated by visual appraisal from other similarly
defined groups within the same species, or a group for which geographical and/or cultural
separation from phenotypically similar groups has led to acceptance of its separate identity
Breed
— The mean genetic value of an individual as a parent. It can be estimated as
the average superiority of an individual’s progeny relative to all other progeny under
conditions of random mating.
Breeding value
— Spindle-fiber attachment region of a chromosome.
Centromere
— Microscopically observable linear arrangement of DNA in the nucleus of a cell.
Chromosome
— Alleles, each of which produces an independent effect in heterozygotes
Co-dominant alleles
The mean performance of a line when involved in a cross-breeding system.
Combining ability —
A line that is randomly selected and randomly mated. Usually used in selection
experiments to monitor environment effects in order to estimate genetic change in a selected
line.
Control line —
— Matings between animals of different breeds or lines
Crossbreeding
— The protoplasm outside a cell nucleus.
Cytoplasm
— An individual descended from other individuals.
Descendant
— Deoxyribonucleic acid, the chemical material which carries information to code for a
gene.
DNA
— Applied to one member of an allelic pair of genes, which has the ability to express
itself wholly or largely at the exclusion of the expression of the other allele
Dominant
— The aggregate of all the external conditions and influences affecting the life
and development of the organism.
Environment
— A prediction of a breeding value. See breeding value
Estimated breeding value
— When the gene at one locus affect the expression of the gene at another locus
Epistasis
— A sequence of DNA that is expressed (transcribed) into RNA , then translated into
protein.
Exon
— Animals resulting from crossing parents from different lines or breed
F1
— Animals resulting from matings among F1 parents
F2
— Animals resulting from matings among F2 parents
F3
The mean number of offspring per parent that successfully reproduce
Family size —
— Individuals having the same male and female parents
Full sibs
— A sperm or egg cell containing the haploid (1n) number of chromosomes .
Gamete
— A functional hereditary unit that occupies a fixed location on a chromosom
Gene
— A gene or DNA sequence having a known location on a chromosome and
associated with a particular gene or trait; a gene phenotypically associated with a particular,
easily identified trait and used to identify an individual or cell carrying that gene.
Genetic marker
— Variation in phenotype which results from variations in genetic composition
among individuals.
Genetic variance
— The complete set of genes and non-coding sequences present in each cell of an
organism, or the genes in a complete haploid set of chromosomes of a particular organism.
Genome
— A discipline in genetics concerned with the study of the genome of an organism.
Genomics
— The genetic constitution of one or a few gene(s) or locus (loci), or total genetic
make-up (genes) of an individual organism.
Genotype
— The process of repeated backcrossing to one parental line to produce a population
that is nearly purebred.
Grade-up
Individuals that share only one common parent
Half sibs —
— A set of alleles at a closely linked group of loci, so closely linked that the allelic set
behaves almost as one allele in terms of inheritance
Haplotype
— Degree to which a given trait is controlled by inheritance; proportion of total
phenotypic variation that is attributable to genetic variation (in contrast to environmentcaused variation).
Heritability
— The degree to which the performance of a crossbred animal is better or worse than
the average performance of the parents.
Heterosis
An organism with unlike members of any given pair or
series of alleles, which consequently produces unlike gametes
Heterozygote, adj. heterozygous —
— Chromosomes which occur in pairs and are similar in size and
shape, one having come from the male and one from the female parent.
Homologous chromosomes
— An organism whose chromosomes carry identical members
of a given pair of genes. The gametes are therefore all alike with respect to this locus
Homozygote, adj. homozygous
— Matings among related individuals, which results in progeny that have less
heterozygosity and hence more homozygous gene pairs than the average of the population.
Inbreeding
— When animals are culled if they do not meet all of the minimum levels
of performance for a set of traits.
Independent culling
— The appearance of the metaphase chromosomes of an individual or species, which
shows the comparative size, shape, and morphology of the different chromosomes.
Karyotype
— A gene that results in the death of the animal.
Lethal gene
— Both internal (e.g., genetic merit) and external (e.g., nutrition, disease, exposure)
forces that influence the expression of a threshold character (e.g., disease, conception,
abnormalities, etc.).
Liability
— Mating of selected individuals from successive generations to produce animals
with a high relationship to one or more selected ancestors. It is a mild form of inbreeding
Line-breeding
— Association of genes physically located on the same chromosome. A group of linked
genes is called a linkage group.
Linkage
— The advantage of the crossbred mother over the average of purebred
mothers.
Maternal heterosis
— The rules which describe how selected breeds and/or individuals will be
paired at mating.
Mating systems
— The process by which the chromosome number of a reproductive cell becomes
reduced to half the diploid (2n) or somatic number and results in the formation of eggs or
sperm.
Meiosis
— Movement of animals, and consequently genes, from one population to another.
Migration
— Refers to the frequency at which the less common allele occurs
in a given population.
Minor allele frequency (MAF)
— Small bodies in the cytoplasm of most plant and animal cells responsible for
energy production.
Mitochondria
— Cell division process in which there is first a duplication of chromosomes, followed
by migration of chromosomes to the ends of the spindle and a dividing of the cytoplasm,
resulting in the formation of two cells with diploid (2n) number of chromosomes.
Mitosis
— The branch of genetic studies that deals with hereditary transmission and
variation on the molecular level. It deals with the expression of genes by studying the DNA
sequences of chromosomes.
Molecular genetics
— Three or more alternative forms of a gene representing the same locus in a
given pair of chromosomes
Multiple alleles
— A sudden change in the genotype of an organism. The term is most often used in
reference to point mutations (changes in base sequence within a gene), but can refer to
chromosomal changes
Mutation
— Natural processes favoring reproduction by individuals that are better
adapted, and tending to eliminate those less adapted to their environment.
Natural selection
— Part of a cell containing chromosomes and surrounded by cytoplasm
Nucleus
— Mating of individuals that are less closely related than the average of the
Outcrossing
— Usually refers to pedigree chart or what a
Pedigree
— The proportion of the individuals with a particular gene combination that express
the corresponding trait.
Penetrance
— Environmental effects that result in permanent effects on
the phenotypic expression of a trait.
Permanent environmental effects
— Genetically determined characteristic which can be possessed by an organism. A
synonym of trait.
Phene
— The set of all phenotypes expressed by a cell, tissue, organ, organism, or species
Phenome
— Actual exhibit of observable traits. Normally, it refers to physical characteristic of
an individual such as size, shape, color, or performance.
Phenotype
— When two traits tend to change in the same or different direction as
a net result of genetic and environmental effects.
Phenotypic correlation
— A performance record; a measure of an animal’s performance for a trait.
Phenotypic value
— Variation in phenotype which results from variation in genetic and
environmental effects on the individuals.
Phenotypic variation
— Where DNA or genes have more than two forms or alleles in the population
Polymorphism
— Entire group of organisms of a kind that interbreed.
Population
— The branch of genetics which deals with frequencies of alleles in groups
of individuals.
Population genetics
— Offspring or individuals resulting from specific matings.
Progeny
— A test used to help predict an individual’s breeding values, involving multiple
matings of that individual and evaluation of its offspring.
Progeny test
— Any of a group of complex nitrogenous organic compounds that contain amino acids
as their basic structural units, occur in all living matter, and are essential for the growth and
repair of animal tissue.
Protein
— A trait that can generally be classified into a limited number of categories,
and the animal can be said to “possess” the quality or not
Qualitative trait
— A trait that is represented by an almost continuous distribution of
measurements.
Quantitative trait
) — A locus that affects a quantitative trait.
Quantitative trait locus (QTL
— A mating system in which animals are assigned as breeding pairs at random,
without regard to genetic relationship or performance.
Random mating
— Applies to one member of an allelic pair which lacks the ability to manifest itself
Recessive
— Ribonucleic acid, involved in the transcription of genetic information from DNA
RNA
— The separation of paired alleles at loci during germ cell formation
Segregation
— Any natural or artificial process favoring the survival and propagation of certain
individuals in a population
Selection
— The linear arrangement of nucleotides that make up unbranched polymer chains
of DNA or RNA.
Sequence
— The X or Y chromosomes
Sex chromosomes
— A distinct variant of a phenotypic character of an org
Trait
— The allele at a particular SNP that is the least frequent in a population
Variant allele
— The cell produced by the union of mature gametes (egg and sperm) in reproduction
Zygote
is the biology of heredity and variation that mainly deals with the way in which
traits of the parents are passed on or transmitted to their offspring
Genetics
is a branch of genetics, which is concerned with the proper selection and use of
the traits of the parents to produce offspring with predictable and desirable traits for the
improvement of animals in general.
Breeding