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Homework #1 is posted and due 9/20 Bonus #1 is posted and due 10/25

Homework #1 is posted and due 9/20 Bonus #1 is posted and due 10/25 For Bonus points, today’s quiz is due T 9/18. DNA is used to produce RNA and/or proteins, but not all genes are expressed at the same time or in the same cells. How do cells control which genes are expressed?. Protein.

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Homework #1 is posted and due 9/20 Bonus #1 is posted and due 10/25

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  1. Homework #1 is posted and due 9/20 • Bonus #1 is posted and due 10/25 • For Bonus points, today’s quiz is due T 9/18

  2. DNA is used to produce RNA and/or proteins, but not all genes are expressed at the same time or in the same cells. How do cells control which genes are expressed? Protein

  3. Cells and organisms must monitor and respond to the environment. Is there anybody out there?

  4. Signal Transduction External Stimulus Internal Effector… Effector Effector Effector Response Perception (by receptor) Stimulus

  5. Signal transduction step by step: Perception

  6. Signal transduction step by step: Transduction

  7. Signal transduction step by step: Response – such as changes in cellular components or production of new cellular components

  8. Transduction can involve activation or inactivation of proteins.

  9. Cellular responses may involve changes in the expression of genes.

  10. Blood sugar levels as an example of cellular responses to the environment

  11. Why so many steps?

  12. Multiple steps allow for signal specificity. Different relay molecules lead to different responses

  13. Multiple steps allow for signal amplification: Calcium is a simple method of amplifying signals

  14. Calcium is a common effector. Cytoplasmic calcium levels are normally low.

  15. During signal transduction, calcium can be released into the cytoplasm: Perception

  16. During signal transduction, calcium can be released into the cytoplasm: Transduction

  17. During signal transduction, calcium can be released into the cytoplasm: Response

  18. During signal transduction, calcium can be released into the cytoplasm

  19. General model of Ca++ signaling

  20. General model of Ca++ signaling

  21. Multiple steps allow for signal amplification: Calcium is a simple method of amplifying signals

  22. Ca++ is involved in many responses

  23. in Plants Development Cold Guard cell closing Osmotic shock Light Fungal infection Touch Pollen tube growth Wounding… in Animals Neurons Muscle movement Wounding Development Fertilization Hormones … Ca++ is involved in signal transduction for responses of: How can there be specificity?

  24. Everything has its place…

  25. Some Ca++ channels have specific effectors associated with them: Micro-domains Ikeda, Science 12 Oct 2001 Vol 294:318-319

  26. Root nodules: Nitrogen fixation

  27. Bacteria and Plants Symbiosis

  28. Signaling between bacteria and plants

  29. 1nM Nod 10nM Nod A biphasic Ca++ response to Nod factor: 1nM Nod - toward nucleus 10nm Nod - away from nucleus Fig 3. Shaw and Long, Plant Physiology, March 2003, Vol. 131, pp. 976–984

  30. 1nM Nod 10nM Nod 10nM Nod 1nM Nod A biphasic Ca++ response to Nod factor: 1nM Nod - toward nucleus 10nm Nod - away from nucleus Fig 3. Shaw and Long, Plant Physiology, March 2003, Vol. 131, pp. 976–984

  31. Everything has its place…

  32. 2 hypotheses about how Ca++ signals are transduced: Signatures vs. Switches Fig 1. Scrase-Field and Knight, Current Opinion in Plant Biology 2003, 6:500–506

  33. Photosynthesis: Plants can make sugar using energy from the sun, water from the ground, and CO2 from the air.

  34. Stomata regulate gas exchange: CO2 in, O2 and water out H2O H2O

  35. Stomata open closed

  36. Opening and closing of stomata

  37. Ca++ fluxes in guard cells in response to hormone or stress that cause stomatal closing. Wildtype vs. det3 and gca2: mutants that fail to close stomata following treatment Fig 5. Sanders et al., The Plant Cell, S401–S417, Supplement 2002

  38. 2 hypotheses about how calcium signals are transduced: Signatures vs. Switches Fig 1. Scrase-Field and Knight, Current Opinion in Plant Biology 2003, 6:500–506

  39. in Plants Development Cold Guard cell closing Osmotic shock Light Fungal infection Touch Pollen tube growth Wounding… in Animals Neurons Muscle movement Wounding Development Fertilization Hormones … Ca++ is involved in signal transduction for responses of: How can there be specificity?

  40. Homework #1 is posted and due 9/20 • Bonus #1 is posted and due 10/25 • For Bonus points, today’s quiz is due T 9/18

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