Mendel’s Laws of Heredity Gregor Mendel (1822- 1884)– Conducted experiments with pea plants and laid the foundation for the study of genetics Mendel’s Laws of Heredity

endel Genetics – Scientific study of heredity What is heredity? What are traits?

Peas are self-pollinating Mendel Peas are self-pollinating Pollination Fertilization Gametes Zygote

11.1 Mendel Why is self pollination a problem?

11.1 Notice the parental generation is the P generation WHAT WAS THE OUTCOME???

ALL YELLOW Mendel Why did the other parent’s trait disappear?? Notice that this is the F1 generation, the first filial generation ALL YELLOW

Mendel Mendel's first conclusion was that inheritance is determined by factors passed from one generation to the next. These factors are…. Genes Alleles

Mendel Mendel’s second conclusion was that some of these alleles are dominate Principle of dominance.

Mendel Did the recessive alleles disappear or were they still present in the F1 generation???

Mendel What did Mendel conclude from this? The Law of Segregation

Mendel

Mendel Genotype Phenotype

Punnett Squares Monohybrid cross Now we need to segregate their alleles Now we can cross our alleles First we need parents Anything with a dominate allele displays the dominate trait Now we need to give them genotypes Tt Tt t tt Tt Tt t

11.2 Punnett Squares Homozygous Heterozygous

Like monohybrid crosses except with two traits. Dihybrid Crosses Like monohybrid crosses except with two traits. We could predict a cross between two pea plants that are both heterozygous for yellow color and smooth seeds (opposite would be wrinkled). What are their genotypes? RrYy and RrYy

Dihybrid Cross To find the gametes for the outside of the punnet square you can use FOIL: (Rr)(Yy) First – RY Outside – Ry Inside – rY Last – ry

RY Ry rY ry RRYY RRYy RY Ry rY ry

Independent Assortment The results from this cross show that the alleles for seed shape segregate independently from alleles for seed color. One gene does not effect the inheritance of another gene During the formation of gametes genes for different traits segregate independently