1. Plant Hormones and the Endocrine System Chapters 39 and 45 (in brief) Campbell Reece

2. Cell Communication in Plants

3. Response  2 main types of responses:  Increased or decreased transcription of mRNA to make enzymes  Activation of existing enzymes

4. Plant Hormones  AKA Plant Growth Regulator  Almost all aspects of plant growth and development are under hormonal control to some degree  A single hormone may regulate many different processes  Multiple hormones may influence a single process  Response depends mostly on the amount of a hormone compared with other hormones

5. Plant Tropisms  Growth response toward or away from stimuli  Phototropism – response to light  Gravitropism – response to gravity  Thigmotropism – response to touch

6. Hormones in Animals  A molecule that is secreted into the extracellular fluid, circulates in the blood or hemolymph, and communicates regulatory messages throughout the body  Hormones elicit a specific response from its target cells, but cells lacking the receptor for that hormone are unaffected  Endocrine system – regulates reproduction, development, energy metabolism, growth, and behavior

7. Types of Signaling Molecules  Hormones – secreted by endocrine cells or glands  Travel via blood or hemolymph throughout body  Local regulators – reach target cells solely by diffusion  Paracrine signaling – target cells lie near secreting cell  Autocrine signaling – target cell is itself

8. Types of Signaling Molecules  Neurotransmitters – cross synapses  Neurohormones – specialized neurons secrete molecules into the bloodstream to reach target cells  Pheromones – chemicals that are released into the external environment

10. Chemical Classes of Hormones

11. Cellular Response Pathways  Water-soluble hormones travel freely through the bloodstream, bind to cell- surface signal receptors  Change molecules in the cytoplasm OR regulate gene transcription  Lipid-soluble hormones travel in the bloodstream bound to transport proteins, diffuse across the membrane, bind to an intracellular signal receptor  Regulates gene transcription

13. Multiple Effects of Hormones  Many hormones create more than one type of response in the body  The type of response depends on the molecules that receive or produce the response

14. Negative Feedback

15. Positive Feedback