Breeding and Genetics Terminologies

Flashcards covering key terminology in breeding and genetics.

Atavism

Reappearance of a character after it has not appeared for one or more generations.

Backcross

Crossing of F1 offspring with either parental breeds.

Blocky

Refers to deep, wide, and low-set animals.

Burro

A donkey or ass.

Calf Crop

The number or percentage of calves produced in a herd within a year.

Autosomes

Chromosomes other than sex chromosomes.

Catalo (Cattalo)

Crossbred between American bison and domestic cattle.

Crossing Over

Exchange of parts of homologous chromosomes during meiosis.

Epistasis

Interaction of two or more pairs of genes that are not alleles to produce a phenotype that they don’t produce when they occur separately.

Heritability Estimate

An estimate of the proportion of the total phenotypic variation in a population that is due to heredity.

Karyotype

Chromosomes of a plant or animals that at metaphase stage of cell division.

Locus

Region of chromosomes or pairs of homologous chromosomes where a particular gene is located.

Multiple Alleles

A series of more than two alleles which occupy the same location in homologous chromosomes.

Nicking

The production of progeny that are superior to the parents which produce them.

Nucleotide

A chemical compound composed of a nitrogen base, a sugar and phosphate molecule.

Nulliparous

Females that never give birth to a young.

Outcross

Mating of an individual to another within the same breed which is not closely related to it.

Overdominance

Interaction of the members of a pair of genes to produce a phenotype more superior in heterozygote than either homozygote.

Phenocopy

Production of a particular phenotype by an environment that is also produced by heredity.

Pleitrophy

A situation where one gene affects two or more traits.

Polygenic Inheritance

A trait determined by many pairs of genes.

Ridgling (Rigling)

Cryptorchid.

Synapsis

Coming together of paired chromosomes during first meiotic division.

Test Cross

A test to determine if the individual is a carrier of a recessive gene.

Variance

Amount of variation within a population.

Chromosomes

Cell material that acts as the means for transporting genes during cell division.

Genes

The units or factors of heredity that are responsible for the expression of any characteristic.

Genetics

The science or study of heredity and variation.

Genetic Variation

The differences in genetic makeup that exist among animals.

Inbreeding

Practice of mating animals more closely related than the average of the population.

Lethal Gene

A gene which causes the death of the animal, usually before or at birth.

Linebreeding

A mild form of inbreeding to maintain a relationship to some outstanding ancestor.

Longevity

Length of useful life.

Penetrance

The ability of a gene or group of genes to cause their characteristic to develop.

Persistency

The degree to which a character is maintained during longevity.

Predicted Transmitting Ability (PTA)

Estimate of genetic superiority that an animal will transmit to an offspring.

Progeny Test

The evaluation of an animal based upon the performance or appearance of its offspring.

Alleles

Different versions of the same gene found at the same locus.

Codominant Alleles

Two alleles that have different effects distinguishable in a heterozygous individual.

Crossbreeding

Crossing two different breeds.

Dominant Allele

One that determines the phenotype even when there is only one copy.

Drift

Changes in allele frequencies over time due to chance.

Epistasis

One gene's expression prevents the expression of another.

Fixation

Loss of all alleles of a gene.

Gene Dropping

Loss of alleles due to genetic drift.

Genetic Bottleneck

When population numbers are temporarily reduced to a level insufficient to maintain diversity.

Genetic Diversity

Expressed as percentage of genes that are polymorphic or heterozygous.

Genome

The total genetic makeup of an organism.

Heterozygous

Carrying two different alleles of a gene.

Heterozygous Advantage

The heterozygous genotype shows the highest relative fitness.

Heterozygous Insufficiency

When the heterozygous genotype lacks sufficient gene product for normal phenotype.

Heterosis

Crossing two inbred lines yields more vigorous progeny than their parents.

Linkage

Frequency with which two genes on the same chromosome remain together during gamete formation.

Allele Frequency

The fraction of all alleles of a gene in a population that are of one type.

Outcrossing

Mating two individuals of the same breed that are sufficiently unrelated.

Recombination

The reciprocal exchange of portions of two homologous chromosomes during gamete formation.