1. Drosophila Genetics

2. Drosophila Life Cycle • Four stages • Egg • Larva • Pupa • Adult

3. Sex Determination • Male • Smaller • Abdomen rounded • Tipped with black • Female • Bigger • Abdomen pointed

4. Culture Vial • Lay your vial on its side. • Gently brush all the adult flies of the SIDE WALL of the vial. • DO NOT SET THE VIAL UPRIGHT! • Count all the flies and determine their phenotype. • Enter the data in the corresponding table of the lab.

5. Sex Linked Inheritance • In sex-linked inheritance, alleles on sex chromosomes are inherited in predictable patterns. • In Drosophila the locus for eye color is located on the X chromosome. • The allele for red eye color, which is normal in wild flies, is dominant to the mutant allele for white eyes.

6. Male with White Eye • As females have two chromosomes X (with a locus for eye color), they might be homozygous (XR XR) or heterozygous (XR Xr) for either allele.

7. Male with Vestigial Wings • Males, who carry only one (XY) chromosome, are always hemizygous. • They carry only the one X chromosome inherited from their mother, and it determines their eye color, so a fly Xr Y will have white eyes, while a XR Y will have red eyes • The same concept applies to vestigial wings

9. Males and Females

11. Vestigial (short) and Wild type wings (long)

12. Genotypes WW – Wild (long wings) Ww – Wild (long wings) ww – vestigial (short wings) - mutation XRXR - Red eyed female XRXr – Red eyed female XrXr - White eyed female XR Y – Red eyed male Xr Y – white eyed male

13. Mutations • Mutation – sudden genetic change (change in base pair sequence of DNA) which can be passed to future generations. (ie vestigial wings)

14. WildWings/ White Eyes Short Wings/ Red Eyes WildWings/ Red Eyed Female WwXRXr WildWings/ Red Eyed male WwXRY

17. WwXRXr WXR WX rwXRwXr WXR WwXRY WY wXR wY

19. Obtain Chi-Square number