Animal Breeding & Genetics Lecture Notes

A comprehensive set of vocabulary flashcards covering the fundamentals of animal genetics, breeding history, Mendelian laws, biotechnological applications, and common genetic terminology based on the MFValdez compilation.

Animal Genetics

The study of how traits are passed down from parents to offspring in animals.

Animal Breeding

The art and science of using the principles of Animal Genetics to improve animals by enhancing desirable traits.

Mendelian/Classical Genetics

A discipline in genetics that focuses on how genes are inherited over generations.

Population Genetics

The study of how genetic variation and traits are inherited within groups of individuals.

Molecular Genetics

The study of the molecular structure and function of genes.

Gregor Johann Mendel

The scientist who discovered the laws of heredity through experiments with garden peas, laying the foundation for modern genetics.

Wilhelm Johannsen

The scientist who coined the term "gene" for the basic unit of inheritance.

T.H. Morgan

The developer of the linear theory of genes who explained genetic crossing over and created the first chromosome maps using fruit flies.

Robert Bakewell

A pioneer in animal breeding who developed the shire horse, longhorn cattle, and Leicester sheep.

Phenotype ($P$)

The observable manifestation, such as appearance or performance, of a given character of an individual.

Genotype ($G$)

The genetic makeup of an individual consisting of alleles inherited from parents.

Environment ($E$)

External factors influencing phenotype, including non-genetic factors like nutrition, physical environment, and management practices.

Genotype by Environment interaction ($GxE$)

The interaction where certain genotypes perform better under specific environments compared to others, expressed in the formula $P = G + E + (GxE)$.

Law of Segregation

Mendel's law stating that factors (genes) appear in pairs and separate during gamete formation, with each gamete randomly receiving one member of the pair.

Law of Independent Assortment

Mendel's law stating that genes for different traits assort independently during gamete formation, meaning traits are inherited separately.

Law of Dominance

Mendel's law stating that in a cross of homozygous parents with contrasting traits, only the dominant trait appears in the $F1$ generation.

Alleles

Alternate forms of a gene.

Locus

The specific physical location of a gene on a chromosome.

Diploid

Cells that contain two complete sets of chromosomes, one from each parent (e.g., humans have $46$ chromosomes in each diploid cell).

Haploid

Cells that contain only one complete set of chromosomes, such as egg and sperm cells.

Cattle ($Bos\,taurus$) Chromosome Number

Cattle possess a diploid chromosome count of $60$.

Hardy-Weinberg Law

A principle stating that in a large, randomly mating population, gene and genotype frequencies remain constant from generation to generation if no external forces act on them.

Genetic Drift

Changes in gene frequency in small breeding populations due to chance fluctuations.

Meiosis

A two-stage cell division process that reduces the number of chromosomes by half, resulting in four haploid daughter cells from a single diploid cell.

Crossing Over

The exchange of genetic material between homologous chromosomes during prophase I of meiosis.

Point Mutation

A genetic mutation where one base in the DNA sequence is changed.

Inversion Mutation

A mutation where a segment of DNA is reversed end to end.

Incomplete Dominance

A non-Mendelian inheritance pattern where heterozygous individuals display an intermediate phenotype instead of a typical dominant-recessive relationship.

Codominance

A condition where both alleles at a gene locus are fully expressed, resulting in a phenotype that shows both traits.

Epistasis

An interaction where one gene affects the expression of another gene at a different locus.

Culling

The process of removing inferior animals from a breeding population.

Pedigree Selection

The practice of selecting breeding animals based on the performance records of their ancestors.

Progeny Testing

Evaluating an individual's breeding value by assessing the average performance of its offspring.

Selection Index

A method of scoring each trait and summing the scores to decide which animals to cull based on the lowest total values.

Heterosis (Hybrid Vigor)

The increased performance or superiority of crossbred offspring compared to the average of their purebred parents.

Inbreeding

The mating of individuals that are closely related.

Linebreeding

A mild form of inbreeding involving the mating of cousins, grandparents with grandchildren, or half-siblings.

Test Cross

Mating an individual with an unknown genotype to a homozygous recessive individual to determine the unknown genotype.

MOET (Multiple Ovulation Transfer Technology)

A fast-breeding method where a female animal is given hormones like $FSH$ to induce superovulation for herd development.

Sperm Sexing

A process where X-bearing sperm cells are separated from Y-bearing sperm cells.

Mosaicism

A condition where an individual derived from one zygote possesses two or more distinct genotypes.

Chimerism

A condition where an individual is derived from two or more zygotes and has different chromosomal types, such as a goat-sheep chimera.

Breeding Value

The mean genetic value of an individual as a parent, estimated as the average superiority of its progeny relative to others under random mating.

Pleiotropy

The production of two or more apparently unrelated phenotypic effects by a single gene.

Transcription

The process by which genetic information is copied from DNA to RNA.

Translation

The process by which a protein is synthesized from the information contained in a molecule of messenger RNA.