1. 1. What is a mutant? 2. How is hereditary information passed on from one generation to the next? What are the rules? 3. The same rules apply to all plants and animals. Concepts

6. Normal Fly

7. White Eyes Mutant

8. Dark Body Mutant

9. Tiny Wing Mutant

10. Wings Held-Out Mutant

11. A mutant is different than “normal”. The mutant characteristic is passed on to the next generation.

12. normal wing mutant Fruit Flies

13. normal wing mutant

14. Plants and animals have two copies of every gene. Mom and dad each pass on only one copy of every gene to their children. Genes are the basic units of inheritance.

15. One “good” copy of a gene is all that is needed to be normal. A mutant has two “bad” copies of a gene. Genes can be working (“good”) or broken (“bad”).

16. Each offspring gets one copy of the gene from each parent. All offspring are normal. normal (has 2 good copies of wing gene) normal (has 2 good copies of wing gene) +/+ x parents: +/+ offspring: x

17. Each offspring gets one copy of the gene from each parent. All offspring have 2 bad copies of wing gene. All offspring are wingless. -/- x parents: -/- offspring: wingless mutant (has 2 bad copies of wing gene) wingless mutant (has 2 bad copies of wing gene) x

18. normal (has 2 good copies of wing gene) mutant (has 2 bad copies of wing gene) +/- offspring: All offspring look normal because they only need one good copy of the wing gene. All offspring are “carriers” for a mutant copy of the wing gene. +/+-/- x parents: x

19. carrier + / - x offspring: +/-+/--/+-/+-/--/- These flies look normal because they only need one good copy of the wing gene. These flies have no wings because they have two bad copies of the wing gene. +/++/+ x

20. Cells Communicate with Each Other Through Signals and Receptors

21. Cells Communicate with Each Other Through Signals and Receptors Some signals are secreted and can travel several cells away.

22. Cells Communicate with Each Other Through Signals and Receptors Some signals are tethered and can only influence adjacent cells.

23. Cells Communicate with Each Other Through Signals and Receptors Receptors sense signals and become activated. Activated receptors act to alter gene expression.

24. A Morphogen is a Developmentally Important Type of Secreted Signal Morphogens have the following characteristics: 1. They are synthesized in some but not all cells. 2. They diffuse from the site of synthesis and are less concentrated the farther away from the source of synthesis. 3. Cells respond to different morphogen concentrations by activating expression of distinct sets of genes.

25. Morphogens

26. The dpp gene promotes skin development. In dpp mutants, skin is replaced by nervous system.

27. The dpp gene is normally expressed in cells that will form skin. What would happen if the dpp gene was misexpressed in cells that would normally form the nervous system?

28. Misexpression Experiment Ventral Normal embryo Dorsal Misexpression of dpp converts cells that would normally form nervous system into skin.

29. The ag gene promotes stamen development normal ag mutant petal stamen

30. The ag gene is normally expressed in stamens normal ag mutant What would happen if the ag gene was misexpressed in cells that would normally form petals?

31. Misexpression Experiment ag mutantnormalag misexpression Misexpression of ag causes cells that would normally form petals to form stamens.