Chapter 11 Sections 11.1 and 11.2 The Work of Gregor Mendel

Heredity ---the passing of characteristics from parents to offspring. Gregor Mendel --- first person to succeed in predicting how traits are transferred from one generation to the next. “Father of Genetics”. Most research done in 1865. ---1910-genes reside on chromosomes

4. Monohybrid Cross ---- a cross between two plants differing in a single trait. Rule of Unit Factor ---- Mendel concluded there are two factors(genes) for each of its traits.

6. Alleles --- different gene forms such as big T(tall) or little t(short). 7. Rule of dominance --- the observed trait is dominant while the trait that disappears is recessive. Ex. Plants that had one gene for tallness (T) and one for shortness (t) were tall because the gene for tallness is dominant to the gene for shortness.

Mendel’s First Law 1. Law of Segregation --- a parent, therefore, passes on at random, only one gene(allele) for each trait to each offspring.

Mendel’s First Law 1. Law of Segregation --- a parent, therefore, passes on at random, only one gene(allele) for each trait to each offspring.

Mendel’s First Law 1. Law of Segregation --- a parent, therefore, passes on at random, only one gene(allele) for each trait to each offspring.

Mendel’s First Law 1. Law of Segregation --- a parent, therefore, passes on at random, only one gene(allele) for each trait to each offspring.

Mendel’s First Law 1. Law of Segregation --- a parent, therefore, passes on at random, only one gene(allele) for each trait to each offspring.

Important Terms Continued 8. Phenotype --- the way an organism looks, its physical appearance. Ex. – Tall or Short. 9. Genotype --- the gene combination an organism contains. Ex.--- TT, Tt, or tt. 10. Homozygous(Purebred) --- two genes (alleles) for a trait are the same. Ex.--- TT or tt.

11. Heterozygous (Hybrid) --- two genes(alleles) for a trait are different. Ex.---Tt. 12. Dihybrid Cross ---- a cross involving two different traits.

Mendel’s Second Law 2. Law of Independent Assortment --- genes of different traits --- for ex. seed shape & seed color --- are inherited independently of each other.

Finally 13. Punnett Squares --- method of finding possible genotypes in the offspring of a cross. P. 260-262.