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Cell Communication

Cell Communication Chapter 11 Cells need to communicate between themselves to maintain homeostasis. Process by which signal on cell’s surface converted into specific cellular response consists of series of steps - signal-transduction pathway.

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Cell Communication

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  1. Cell Communication Chapter 11

  2. Cells need to communicate between themselves to maintain homeostasis. • Process by which signal on cell’s surface converted into specific cellular response consists of series of steps - signal-transduction pathway.

  3. http://www.mpi-dortmund.mpg.de/departments/dep1/signaltransduktion/image3.gifhttp://www.mpi-dortmund.mpg.de/departments/dep1/signaltransduktion/image3.gif

  4. Yeasts communicate between 2 types of yeast cells to reproduce. • 2 sexes, a and alpha - secrete specific signaling molecule, a factor and alpha factor. • Factors find each other and bind to each other’s receptors.

  5. Also occurs in multicellular organisms. • Some cells release local regulators - influence cells in local vicinity.

  6. Synaptic signaling - nerve cell produces neurotransmitter that diffuses to single cell - is almost touching sender. • Nerve signals travel along series of nerve cells without unwanted responses from other cells.

  7. Plants, animals - hormones to signal at greater distances. • Cells may communicate by direct contact. • Signaling substances dissolved in cytosol pass freely between adjacent cells.

  8. 3 stages to signal transduction. • 1Reception - chemical signal binds to cellular protein at cell’s surface. • 2Transduction - binding leads to change in receptor that triggers series of changes along signal-transduction pathway. • 3Response - transduced signal triggers specific cellular activity.

  9. Receptor proteins present on cells to recognize signal molecules. • Ligand - molecule that binds to another molecule, causes cell to change shape when attached to cell’s receptor. • Receptors usually found on plasma membrane since signals can’t pass through membrane.

  10. http://www.slic2.wsu.edu:82/hurlbert/micro101/images/lock_key.gifhttp://www.slic2.wsu.edu:82/hurlbert/micro101/images/lock_key.gif

  11. 1 type - G-protein-linked-receptor. • Acts as on/off switch; cycles between being active and inactive.

  12. Tyrosine-kinase receptor system helps different systems to function at same time. • System activated - activates other systems at same time.

  13. Ligand-gated ion channels open/close to allow chemical signals to pass through. • Important in nervous system - allow Na+ and K+ move into and out of cell.

  14. http://dir.niehs.nih.gov/dirln/diricp/figures/overview.jpg

  15. Some signals diffuse through plasma membrane; don’t need proteins. • Some are hormones which act on transcription process.

  16. Transduction stage of signal pathway allows for small signal to be amplified - causes large signal. • Protein kinases essential - help to initiate responses.

  17. Some involve 2nd messengers - molecules small enough to pass through membrane.

  18. http://www.du.edu/~kinnamon/3640/second_messengers/levitan11.2.jpghttp://www.du.edu/~kinnamon/3640/second_messengers/levitan11.2.jpg

  19. Response of particular cell to signal depends on particular collection of proteins. • Some pathways actually linked by scaffolding proteins - allows signals to be passed through pathways.

  20. http://www.bnl.gov/bnlweb/pubaf/pr/photos/2004/DNAbinding-300.jpghttp://www.bnl.gov/bnlweb/pubaf/pr/photos/2004/DNAbinding-300.jpg

  21. All proteins involved in signal pathway important - defects in any can cause abnormal signals.

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