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Plant Response

Plant Response. Chapter 39. Plant Reactions. Stimuli & a Stationary Life animals respond to stimuli by changing behavior move toward positive stimuli move away from negative stimuli plants respond to stimuli by adjusting growth & development. Signal Transduction pathway .

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Plant Response

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  1. Plant Response Chapter 39 http://www.bio.kimunity.com

  2. Plant Reactions • Stimuli & a Stationary Life • animals respond to stimuli by changing behavior • move toward positive stimuli • move away from negative stimuli • plants respond to stimuli by adjusting growth & development http://www.bio.kimunity.com

  3. Signal Transduction pathway • signal triggers receptor • receptor triggers internal cellular messengers & then cellular response • Receptor • Signal pathway (2O messengers) • response What kinds of molecules are the receptors? http://www.bio.kimunity.com

  4. Signal Transduction Pathway example 3. Both pathways lead to expression of genes for proteins that function in green in response of plant. http://www.bio.kimunity.com

  5. Plant Hormones • Chemical signals that coordinate different parts of an organism • only minute amounts are required • produced by 1 part of body • transported to another part • binds to specific receptor • triggers response in target cells & tissues http://www.bio.kimunity.com

  6. Plant Hormones • auxins • cytokinins • gibberellins • brassinosteroids • abscisic acid • ethylene http://www.bio.kimunity.com

  7. Phototropism Went (1926) Darwin and Darwin (1880) http://www.bio.kimunity.com

  8. Auxin • Indolacetic acid (IAA) • stimulates cell elongation • near apical meristems • enhances apical dominance • classical explanation of phototropism • asymmetrical distribution of auxin • cells on darker side elongate faster than cells on brighter side http://www.bio.kimunity.com

  9. Zones of meristem growth Shoot Root http://www.bio.kimunity.com

  10. Polarity of auxin transport 1. Auxin picks up H+ between cells & is neutralized 2. Neutral auxin passes through membrane 3. Cellular pH 7 causes auxin to ionize & is trapped in cell 4. Auxin stimulates proton pump 5. Auxin leaves through carriers http://www.bio.kimunity.com

  11. Auxin response Acid growth hypothesis http://www.bio.kimunity.com

  12. Cytokinins • Family of hormones • modified forms of adenine • produced in roots, fruits & embryos • Effects • control of cell division & differentiation • enhances apical dominance • interaction of auxin & cytokinins http://www.bio.kimunity.com

  13. Gibberellins • Family of hormones • over 100 different gibberellins identified • Effects • stem elongation • fruit growth • seed germination http://www.bio.kimunity.com

  14. Brassinosteroids • Steroids • Effects • similar to auxins • cell elongation & division in shoots & seedlings http://www.bio.kimunity.com

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