1. Today’s Agenda: Questions from Chapter 1 Introduce key ideas in
Chapter 2: Single Gene Inheritance

2. Single Gene Inheritance
Identify if the phenotype is due to a single gene…..where do we begin?

3. Start with a look at mutants….
Is this forward or reverse genetics?
What is the inheritance ratio?

4. Genes are part of chromosomes

5. Chromosomes have unique regions
What is the function of each of these regions?

6. Genome of Muntkac How many chromosomes?
Is this organism haploid or diploid?

7. Map of Genes and Chromosomes

8. Map of Genes and Chromosomes

9. Mendel was first to study single gene inheritance

10. What did Mendel find? ? ?

11. The F2 ratios are the same!

12. Mendel’s explanation…law of equal segregation

13. What did Mendel’s work establish?

14. Meiosis is key in the segregation of chromosomes

15. Synapsis increases variation
FIGURE: Model of the synaptonemal complex (SC).  Lateral elements (light blue rods) of homologous chromosomes align and synapse together via a meshwork of transverse filaments (white lines) and longitudinal filaments (dark blue rods).  The longitudinal filaments are collectively referred to as the "central element" of the SC.  Ellipsoidal structures called recombination nodules (e.g., gray ellipsoid) are constructed on the central region of the SC.  (Image: Mississippi Genome Exploration Lab)

16. How are gametes formed in haploid organisms?

17. Single-Gene inheritance at DNA level

18. Map of Mutations

19. More about alleles…… Dominance Recessiveness Haplosufficient
Haploinsufficient

20. What’s unusual about white-eyed fruit flies?
Watch for new terms: What does it mean to be hemizygous? What’s a pseudoautosomal region?

21. Some genes are found on sex chromosomes

22. What is the inheritance pattern of genes on sex chromosomes?

23. Crosses of the F1

24. Pedigrees Analysis to represent inheritance

25. Summary Single gene inheritance patterns
Perform a cross of organisms using wild type and mutant
Confirm the genotype of the wild type by performing a testcross
Look for phenotypic ratios of 3:1, 1:1 and genotypic ratios of 1:2:1
Sex-linked genes have different phenotypic ratios in the two sexes of progeny AND different ratios in reciprocal crosses