Animal Science 1011 Principles of Genetics (exam 2)

Genetics

the study of genes, genetic variation, and heredity

Trait

a distinguishing quality or characteristic

Artificial selection

A method used for the continuous improvement of livestock species

Blending theory

Parental 'essence' blends together resulting in the appearance of their offspring being intermediate

Gregor Mendel

Father of modern genetics

Qualitative traits

traits that can be placed into categories (i.e. horned OR polled)

F1 generation

the first generation of offspring from a cross of two parent plants

F2 generation

the second generation of offspring from self-pollination of the F1 generation

Dominant phenotype

expressed traits that are inherited unchanged in a hybridization

Recessive phenotype

latent traits that disappear in the offspring of a hybridization

Deoxyribonucleic acid (DNA)

self-replicating material present in nearly all living organisms that carries genetic information

Genome

the entire 'set' of DNA; hereditary instructions for building, running, and maintaining an organism

Genes

functional unit of heredity; small region of DNA that codes for a functional molecule (i.e. a protein)

Allele

alternative form of a gene that arises from a mutation in the DNA

Locus (loci)

specific location on a specific chromosome where a gene is found

Homozygous

an individual possessing two of the same alleles

Heterozygous

an individual possessing two different alleles

Punnet square

a 2-dimensional grid used to determine the possible genotypes (and resulting phenotypes) from a mating

Mendel's Law of dominance

a certain allele will be dominant over another, expressing its phenotype and masking the phenotype of the other

Phenotype

the physical expression of the genotype

Partial dominance

the heterozygous organisms possess a phenotype that is intermediate to the homozygous genotypes

Co-dominance

the heterozygous organisms fully express the phenotypes of both homozygous genotypes

Epistasis

the expression of genes at one locus depends on the alleles present at one or more other loci

Simply inherited traits

traits that are controlled by one - a handful of genes and are well-understood

Polygenic traits

economically important traits controlled by tens-hundreds of different genes

Marbling

A trait in animal agriculture that affects the quality of meat.

Birth weight

A trait that measures the weight of an animal at birth.

Milk production

The amount of milk produced by an animal, often measured in liters or pounds.

Egg production

The number of eggs produced by a poultry animal over a specific period.

Homozygous dominant

An organism that has two identical dominant alleles for a particular gene.

Genotype

The genetic constitution of an organism, representing the alleles it possesses.

Complete dominance

A form of dominance where the phenotype of the heterozygote is indistinguishable from that of the homozygous dominant.

No-dominance

A situation where neither allele is dominant, resulting in a phenotype that is a blend of both alleles.

Codominance

A form of inheritance where both alleles in a heterozygote are fully expressed, resulting in a phenotype that shows both traits.

Simply-inherited trait

A trait that is determined by a single gene.

Polygenic trait

A trait that is influenced by multiple genes.

Carcass weight

The weight of an animal's carcass after slaughter, influenced by multiple genes.

Heritability

A measure of how much of the variation in a trait can be attributed to genetic differences among individuals.