The Science of Animal Agriculture Ch. 4 The Science of Genetics

Genetic Basics Gregor Mendel ( ) –first person to develop workable theory transfer of traits –used garden peas –based on purebred strains

Law of Dominance overriding or dominant factors make certain recessive traits disappear

Law of Segregation the alleles responsible for the traits from each parent are separated and then combined with factors from the other parent at fertilization

Law of Independent Assortment Factors for certain characteristics are passed from parents to the next generation separate from the other factors or genes that transmit other traits

Punnett Square Developed by R.C. Punnett illustrates the possible combinations for a particular trait RR R R rr rr Rr

Punnett Square Developed by R.C. Punnett illustrates the possible combinations for a particular trait Rr R r rR RR Rr rr

Genetics Basics genes are in chromosomes –different animals have different chromosome #’s cattle = 30 pairs horses = 32 pairs apples = 34 pairs each allele contains two genes –one by each parent

Selective Breeding the choosing of individuals of a single strain and species artificial selection need to avoid inbreeding

Hybridization the crossing of different species hybrid vigor –the ability of hybrids or strain crosses to exceed the parents in performance most hybrids are sterile

Crossbreeding the mating of unrelated strains of the same species to avoid inbreeding