Part II (Module 1: Definition Of Terms) Flashcards
The cell produced by the union of mature gametes (egg and sperm) in reproduction.
Zygote
The allele at a particular SNP that is the least frequent in a population.
Variant Allele
A distinct variant of a phenotypic character of an organism that may be inherited,
environmentally determined or a combination of the two.
Trait
The X or Y chromosomes.
Sex Chromosomes
The linear arrangement of nucleotides that make up unbranched polymer chains
of DNA or RNA.
Sequence
Any natural or artificial process favoring the survival and propagation of certain
individuals in a population.
Selection
The separation of paired alleles at loci during germ cell formation
Segregation
Ribonucleic acid, involved in the transcription of genetic information from DNA.
RNA
Applies to one member of an allelic pair which lacks the ability to manifest itself
Recessive
A mating system in which animals are assigned as breeding pairs at random,
without regard to genetic relationship or performance.
Random Mating
A locus that affects a quantitative trait.
Quantitative Trait Locus
A trait that is represented by an almost continuous distribution of
measurements. Examples include average daily gain, backfat thickness, and height.
Quantitative Trait
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. Examples include hair color, skin
color, and ear stature.
Qualitative Trait
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 test used to help predict an individual’s breeding values, involving multiple
matings of that individual and evaluation of its offspring
Progeny Test
Offspring or individuals resulting from specific matings
Progeny
The branch of genetics which deals with frequencies of alleles in groups
of individuals.
Population Genetics
Entire group of organisms of a kind that interbreed
Population
Where DNA or genes have more than two forms or alleles in the population.
Polymorphism
Variation in phenotype which results from variation in genetic and
environmental effects on the individuals.
Phenotypic Variation
performance record; a measure of an animal’s performance for a trait.
Phenotypic value
When two traits tend to change in the same or different direction as
a net result of genetic and environmental effects
Phenotypic correlation
Actual exhibit of observable traits. Normally, it refers to physical characteristic of an individual such as size, shape, color, or performance.
Phenotype
The set of all phenotypes expressed by a cell, tissue, organ, organism, or species
Phenome
Genetically determined characteristic which can be possessed by an organism. A
synonym of trait.
Phene
Environmental effects that result in permanent effects on
the phenotypic expression of a trait. For example, severe mastitis during lactation may have a permanent effect on milk production and litter weaning weight for an animal in subsequent
litters.
Permanent Environmental Effects
proportion of the individuals with a particular gene combination that express
the corresponding trait.
Penetrance
Usually refers to pedigree chart or what a pedigree chart represents in genetics. It
is a document to record the ancestry of an individual. Also used to illustrate
the family structure or breeding scheme.
Pedigree
Mating of individuals that are less closely related than the average of the
Outcrossing
contribute to individual fitness and to the evolution of
animal genetic resources. By definition, these traits are also important to the ability of the
animal genetic resource to be sustained in the production environment
Adaptation Traits
Any one of a class of organic compounds containing the amino (NH2) group and
the carboxyl (COOH) group. They are combined to form proteins.
Amino acids
One of a pair, or series of alternative forms of a gene that can occur at a given locus
on homologous chromosomes
Allele
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
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
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.
It carries the genes responsible for the determination and transmission of
hereditary characteristics.
Chromosomes
mean performance of a line when involved in a cross-breeding system
Combining ability
average performance when a breed or line is crossed with two or more other breeds or line
General combining ability
the degree to which the
performance of a specific cross deviates from the average general combining ability of two
lines.
Specific combining ability
Alleles, each of which produces an independent effect in heterozygotes
Co-dominant alleles
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
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
When the gene at one locus affect the expression of the gene at another locus
Epistasis
prediction of a breeding value
Estimated breeding value
sequence of DNA that is expressed (transcribed) into RNA , then translated into
protein
Exon
may be separated by an intron, which is later removed from the RNA
transcript via a splicing mechanism.
Adjacent exons
Animals resulting from crossing parents from different lines or breeds
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
functional hereditary unit that occupies a fixed location on a chromosome, has a specific influence on phenotype, and is capable of mutation to various allelic forms.
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
The discipline in genetics concerned with the study of the genome of an organism. The field includes efforts to determine the entire DNA sequence of organisms and fine-scale
genetic mapping. It also studies intragenomic phenomena such as heterosis, epistasis,
pleiotropy and other interactions between loci and alleles within the genome.
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
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
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
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
appearance of the metaphase chromosomes of an individual or species, which shows the comparative size, shape, and morphology of the different chromosomes.
Karyotype
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
advantage of the crossbred mother over the average of purebred
mothers
Maternal Heterosis
Rules which describe how selected breeds and/or individuals will be
paired at mating.
Mating system
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
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
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
