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Pathways of Communication

Pathways of Communication. TED Video: Bacteria Communicate?. TED Video. Cell to Cell Interactions. Explain the following statement: The sum is greater than the parts. Who speaks?. Cells in constant communication Unicellular OR Multicellular. With other organisms: Cooperation

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Pathways of Communication

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  1. Pathways of Communication

  2. TED Video: Bacteria Communicate? TED Video

  3. Cell to Cell Interactions Explain the following statement:The sum is greater than the parts.

  4. Who speaks? • Cells in constant communication Unicellular OR Multicellular • With other organisms: • Cooperation • Competition • With other cells: • Cooperation • Successful survival

  5. Making the connections.. • Cells excrete layer surround membrane • The ECM! (extracellular matrix) • Aids in: • Structure • Protection Filaments resist TENSION Ground material resists COMPRESSION

  6. ECM in plants • Primary Cell Wall – initial fiber composite (cellulose microfibrils filled with pectin) • Secondary Cell Wall – secreted by some plants • Between membrane & 1º cell wall • [High] of lignin (sturdy)

  7. Layer of pectins between cell walls(or membranes) • “glues” cells • Degradation = Cell separation

  8. ECM in animals • Proteins NOT polysaccharides • Collagen = pliability • Amt varies • # surrounding cells • Cell function (Ex: elastin in lungs) • Structural properties: integral proteins bind to ECM proteins • adjacent cells can bind at common connections in ECM = increased stability

  9. Predict! What would happen if ECM-cell connection was lost? Can you think of an example? • Cells migrate • Ex: malignant cancer

  10. Reinforcement team in the Middle Lamella 2 types of reinforcers: • Tight Junctions – “quilting” formed by connecting proteins in adjacent cells • Create water tight seal • Separate solutions (ie. Stomach fluid/blood) • Dynamic

  11. Tight Junctions

  12. 2. Desmosomes – connections between cytoskeletons of adjacent cells; “bolt” cells

  13. **Cells Selectively Adhere** • Proteins involved in cell binding – cadherins cell specificity Like cells aggregate

  14. Cellular connections…

  15. Mechanisms of Communication the method behind cell “talking” near & far

  16. Close communication in PLANTS!!! • Plasmodesmata – gaps in cell wall, continuous cell membrane & plasma • Smooth ER runs through • Regulated by proteins

  17. How are these different from plasmodesmata?

  18. Close communication in ANIMALS!!! • gap junctions – holes in ECM and membrane specialized proteins admit: • H2O • aa’s • sugar • nucleotide Coordinate reactions (Ex: muscle contractions; heartbeats)

  19. Fig. 11-4 Plasma membranes Gap junctions between animal cells Plasmodesmata between plant cells (a) Cell junctions (b) Cell-cell recognition

  20. Distant communication: 4 STEPS! • Receive • Process • Respond • Terminate

  21. 1. RECEIVE • Signals are chemical “language” (hormones) • Bind/Ligand to receptors (intra- OR extracellular) Characteristics: Cell specific Dynamic – overstimulation = adaptation Potential blockage

  22. 1. PROCESS • Upon receipt, response initiation begins • 2 types: 1. Direct hormone enters binds to receptor complex enters nucleus binds to DNA directs gene expression

  23. 2. Indirect hormone binds to receptor signal transduction begins Receptor protein kinases G-proteins Both Pathways Result in: Conversion of extracellular signal to intracellular message Amplification of a message many times over

  24. G-proteins Coupled Receptors G-protein can activate an enzyme OR an effector that will go on to activate Animations<~ Watch this! Ions, larger compounds (Ex: Ca2+, cAMP)

  25. Ex: Calcium Pathway Maintaining electrical potential across membranes, cofactor for many enzymes

  26. Receptor Protein Kinases • Phosphorylation cascades amplify signal • Activated enzymes induce a signal response

  27. 3. Response • Activity within cell altered by: • Second messengers • Phosphorylation cascades

  28. 4. Deactivation • Built in systems to “turn off” • Hydrolyze GTP/ATP • Stop phosphorylation • Overstimulation

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