1. GENETICS
Definition
Study of how hereditary characteristics (traits) in an individual are transmitted from one generation to the next.
Milestones
Mendel
“Genes and the Rules of Inheritance”
Watson & Crick
“The Structure of DNA”
Human Genome Project
“Sequencing DNA & Cataloging Genes”

2. Levels of Genetic Analysis
Classical
Structure and Behavior of Chromosomes
Nature of Genetic Material
Molecular
Defining DNA Sequences
Recombination
Gene Manipulation
Population
Variation of Genetic Makeups
Inheritance of Traits

3. Mendelian Genetics Gregor Mendel Contributions Law of Segregation
Dominant and Recessive Traits

4. Fig. 23.1

6. Mendel's Studies of Inheritance
Hypothesis Pea plants inherit two “units of information” (genes) for a trait, one from each parent Monohybrid Experiment Parental Monohybrid Cross Design True breeding strains of purple (P) flowered peas were crossed with true strains of white(p) flowered peas. * True breeding = homozygous PP X pp

8. P P p p x

9. FORMATION OF GAMETES
PP x pp P p P p

10. F1 Generation Punnett Square Analysis
PP X pp
P P p

11. F1 Generation Punnett Square Analysis
PP X pp
P P p Pp Pp Pp Pp

12. F1 Generation Punnett Square Analysis
Genotype: Pp Phenotype: Purple

13. F2 Generation Punnett Square Analysis
F1 Generation Monohybrid Cross Design Crossing of two F1 generation plants X Pp Pp

14. P P p p x

15. F2 Generation Punnett Square Analysis
P p P p PP Pp Pp pp

16. F2 Generation Punnett Square Analysis
Genotypes: PP, Pp, pp Phenotypes: Purple White
Genotypic Ratio 1 (25%): Homozygous Dominant 2 (50%): Heterozygous 1 (25%): homozygous recessive Phenotypic Ratio 3 (75%): Purple 1 (25%): White

17. MENDELIAN GENETICS Conclusions
1) Each trait (gene) has two forms (alleles) which segregate at the formation of gametes
2) One allele which is dominant masks the appearance of the other allele which is recessive.

18. Dihybrid Experiment Parental Dihybrid Cross Design
True breeding strains of peas that were homozygous for red (R) flower color and green (G) seed pod color were crossed
with true breeding strains that were homozygous for white (r) flower color and yellow (g) seed pod color.

19. R R r r G G g g x

20. R R R

21. INDEPENDENT ASSORTMENT
RRxRR GGxGG RRxRR GGxGG
RRGG
RRGG RG RG RG RG

22. INDEPENDENT ASSORTMENT
rrxrr ggxgg rrxrr ggxgg
rrgg
rrgg rg rg rg rg

23. F1 Generation Punnett Square Analysis
RRGG X rrgg rg rg rg rg RG
RrGg
RrGg
RrGg

24. F2 Generation Punnett Square Analysis
F1 Generation Dihybrid Cross
Design
Crossing two F1 generation plants
RrGg X RrGg
Possible Gametes
RG, Rg, rG, rg

25. R r r R r G g G g g x

26. INDEPENDENT ASSORTMENTg G G g

27. INDEPENDENT ASSORTMENT
RRxrr GGxgg RRxrr GGxgg
RRGG
rrgg rg RG rg RG

28. INDEPENDENT ASSORTMENT
RRxrr GGxgg RRxrr ggxGG
RRgg
rrGG rG Rg rG Rg

29. RG Rg rG rg RG Rg rG rg
RRGG
RRGg
RrGG
RrGg
RRgg
Rrgg
rrGG
rrGg
rrgg

30. F2 Generation Punnett Square Analysis
Genotypes RRGG RRGg RrGg RrGG Rrgg RRgg rrGG rrgg Phenotypes Red Flowers, Green Pods Red Flowers, yellow pods white Flowers, Green pods white flowers, yellow pods
Genotypic Ratios 1: RRGG 2: RRGg 4: RrGg 2: RrGG 2: Rrgg 1: RRgg 1: rrGG 1: rrgg 2: rrGg Phenotypic Ratios 9: Red, Green 3: Red, yellow 3: white, Green 1: white, yellow

31. DYHIBRID CROSS Conclusion
Independent Assortment
1)As meiosis ends, genes on pairs of homologous chromosomes have been sorted out for distribution into one gamete or another, independently of gene pairs on other chromosomes.
2) Independent Assortment leads to genetic diversity in populations.