1. History of Genetics Biology

2. Genetics How characteristics are transmitted from parents to offspring

3. Gregor Mendel

4. worked with Pisum satium (pea plant) Gregor Mendel (1822-1884)

5. Flower color Flower position along stem Seed color Seed shape Pod shape Pod color Stem length Mendel studied 7 characteristics

6. Mendel’s Experiments Mendel’s First Cross Crossed “purebred” purple with “purebred” white + P (parent) generation - F 1 – purple Crossed F 1 hybrids + produced F 2 generation - 3 purple : 1 white

7. Alternative versions of genes (alleles) account for variations in inherited characters. + each gene resides at a particular location of a chromosome and can exist in variable forms (two different forms for flower color) Mendel’s Ideas of Inheritance P p Pp

8. Mendel’s Ideas of Inheritance For each characteristic, an organism inherits two alleles, one from each parent. + an organism is either homozygous (two of the same alleles) or heterozygous (two different alleles) Homozygous Heterozygous

9. If the two alleles differ, the dominant allele is fully expressed and the recessive allele has no noticeable affect on appearance. + heterozygotes express the dominant trait Mendel’s Ideas of Inheritance RRrr Rr

10. The two alleles for each character segregate during gamete production. + ovum/sperm get only one of the two alleles (haploid) Mendel’s Law of Segregation

12. P generation Phenotype: Purple/White Genotype: PP/pp F 1 generation Phenotype: Purple Genotype: Pp F 2 generation? Genotype/Phenotype can be predicted using a Punnet Square

13. Mendel’s Law of Independent Assortment Each pair of alleles segregates into gametes independently. WHwHwhWh

15. Mendel’s Law of Independent Assortment Parental Genotypes GGWW ggww Parental Gametes? GW gw GgWw GWGwgW gw F1 Genotypes? F1 Gametes?

16. Beyond Mendel... Different Types of Inheritance:

17. Complete DominanceIncomplete Dominance Mendel’s Traits Snapdragon Color

18. Incomplete Dominance One allele does not dominant the other in the heterozygous condition. Both alleles are expressed but a new phenotype appears that is intermediate. RRrrRr

19. Codominance Both alleles in the Heterozygous condition are dominant. CCCccc

20. Codominance & Multiple Alleles