The study of inheritance of traits

 Austrian Monk  Studied how traits were passed from parent to offspring  His ideas forms the foundation for the basics principles of heredity

 He crossed purebred plants (homozygous)- they only have one form of a gene (two of the same alleles)  When he crossed a purebred plant for yellow seeds and a purebred for green seeds– all offspring had yellow seeds; therefore, he concluded yellow was dominant over green (F1 generation)  Then, he interbred the offspring and noticed the gene for green seeds showed back up in a 3 to 1 ratio. For every three yellow seeded plants there were one green  Mendel studied several traits of the pea plants such as pod color, flower color, etc.

Purebred for green peas (homozygous) Purebred for yellow peas (homozygous) First generation- all yellow (dominate trait) Second generation recessive trait shows back up. 3 to 1 ratio F1 generation – all are hybrids F2 generation Cross pollinates

GenotypePhenotype  A combination of alleles an offspring inherits from parents  Expressed as a pair of letters, ex. Tt  Dominant trait – capital letters  Recessive traits – lower  The traits an organism displays  This is the way the organisms looks

 Used to show and predict the ways alleles can combine in genetic crosses  Need to know the genotypes of each parent

 1. Law of Segregation  2. Law of Dominance  3. Law of Independent Assortment

 Each sex cell receives only one allele from each pair of matching chromosomes.  When sex cells unite the new gene pair contain one gene from each parent

 When two different alleles for a trait are present, one allele is dominant over the other.  Green is the dominant trait where white is recessive

 Genes are not linked.  When sex cells (gametes) are made, the genes for traits found on different chromosomes separate independently.

 Genetics  Alleles  Homozygous  Law of segregation  Heterozygous  Law of dominance  Dominant  Recessive  Genotype  Phenotype  Punnett Square  Law of Independent Assortment

 The allele for tall stems in pea plants is dominant over short stems. Why can you use your observation skills to determine to genotype of a short pea plant but not the genotype of a tall pea plant?