Backcross– a breeding method used to move one or only a few desirable genes from an otherwise undesirable pig line to an elite line. This is done by crossing a donor parent (in genetic engineering this is the transgenic pig) to an elite line, and crossing offspring with the ‘desired gene(s)’ back to the elite parent for several generations.
Biotechnology– using life processes to produce a product useful to humans. Genetic engineering is one example of biotechnology.
Chromosome– DNA is found in large molecules in the nucleus known as chromosomes. Each chromosome is composed of thousands of genes. During cell division, chromosomes duplicate and divide, maintaining the genetic integrity of the organism. With the exception of sex chromosomes, chromosomes come in pairs, giving individuals two copies of each of their genes.
Elite– a line of pigs that have many genes for desirable traits; elite lines are used in the backcross breeding process which results in the desired end product. For example, crossing the transgenic line possessing higher phytase levels with an elite line results in a high-quality pig with decreased environmental impact from phosphorus waste.
Gamete– a mature male or female reproductive cell (sperm or ovum) containing half of the total number of chromosomes in a cell.
Genotype– the allelic composition of a cell or organism, usually represented with a mix of capital and lower case letters.
Hemizygote– an organism that has a gene copy on only one chromosome in a chromosome pair; the other chromosome does not have this gene
Heterozygote – an organism that has two different forms of a gene per cell; one form is at a specific location on one chromosome, the other form is at the same location on the other member of the chromosome pair
Homozygote– an organism that has two identical forms of a gene per cell; each identical gene is found at the same location on both chromosomes of a chromosome pair
Ovary– female reproductive organ in which sex cells are produced
Pedigree – a diagram that shows how traits are passed down through generations
Phenotype – a trait; genotype + environment
Punnett square– a visual depiction of all the possible ways the alleles from two parents could combine.
Somatic cell– a cell, other than reproductive cells, in a living organism.
Transgene– a gene from one organism transferred to another organism using genetic engineering methods
Transgenic line– a pig and the offspring derived from it that have been genetically engineered.