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Chapter 11: Cell Communication

Chapter 11: Cell Communication. 2.e.2 – Timing and coordination of physiological events are regulated by multiple mechanisms (11.1). 3.b.2 – A variety of intercellular and intracellular signal transmissions mediate gene expression (11.1 & 11.4).

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Chapter 11: Cell Communication

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  1. Chapter 11: Cell Communication

  2. 2.e.2 – Timing and coordination of physiological events are regulated by multiple mechanisms (11.1). • 3.b.2 – A variety of intercellular and intracellular signal transmissions mediate gene expression (11.1 & 11.4). • 3.d.1 – Cell communication processes share common features that reflect a shared evolutionary history (11.2 & 11.2). • 3.d.2 – Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling (11.1 & 11.2). Essential Knowledge

  3. 3.d.3 – Signal transduction pathways link signal reception with cellular response (11.3). • 3.d.4 – Changes in signal transduction pathways can alter cellular response (11.4). Essential Knowledge

  4. How do cells communicate? • By “cellular” phones  • But seriously, cells do need to communicate for many reasons. Question?

  5. Cell Communication

  6. Regulation - cells need to control cellular processes • Environmental Stimuli - cells need to be able to respond to signals from their environment Why do cells communicate?

  7. Is a relatively “new” topic in Biology and AP Biology • Appears to answer many questions in medicine • Is a topic you’ll be hearing more about in your future Cell Signaling (C.S.)

  8. 1. Reception - receiving the signal 2. Transduction - passing on the signal 3. Response - cellular changes because of the signal Stages of cell signaling

  9. Reception

  10. The target cell’s detection of a signal coming from outside the cell • May occur by: • Direct contact • Through signal molecules Reception

  11. When molecules can flow directly from cell to cell without crossing membranes • Plants - plasmodesmata • Animals - gap junctions Direct Contact

  12. May also occur by cell surface molecules that project from the surface and “touch” another cell Direct Contact

  13. The actual chemical signal that travels from cell to cell • Often water soluble • Usually too large to travel through membranes Signal Molecules

  14. Behave as “ligands” • A smaller molecule that binds to a larger one Signal Molecules

  15. Usually made of protein • Change shape when bind to a signal molecule • Transmits information from the exterior to the interior of a cell Receptor Molecules

  16. 1. G-Protein linked 2. Tyrosine-Kinase 3. Ion channels 4. Intracellular **You must research these on your own. Receptor Molecules

  17. Most signals never enter a cell • The signal is received at the membrane and passed on • Exception - intracellular receptors Comment

  18. Transduction

  19. The further amplification and movement of a signal in the cytoplasm • Often has multiple steps using relay proteins such as Protein Kinases Signal-Transduction Pathways

  20. The addition of Pi to a protein, which activates the protein • Usually adds Pi to Serine or Threonineamino acids Protein Phosphorylation

  21. General name for any enzyme that transfers Pi from ATP to a protein • About 1% of our genes are for Protein Kinases Protein Kinase

  22. Protein Kinases often work in a cascade with each being able to activate several molecules. • Result - from one signal, many molecules can be activated. Amplification

  23. Small water soluble non-protein molecules or ions that pass on a signal • Spread rapidly by diffusion • Activates relay proteins • Ex: cAMP, Ca +2 Secondary Messengers

  24. Response

  25. May involve: • Regulation of cytoplasmic activities OR • Regulation of transcription Responses

  26. Rearrangement of the cytoskeleton • Opening or closing of an ion channel • Alteration of cell metabolism CytoplasmicRegulation/Response

  27. Otherwise known as nuclear regulation/reponse • Activating protein synthesis for new enzymes • Transcription control factors are often activated by a Protein Kinase Transcription Regulation/Response

  28. Chapter focused only on activatingsignals • There are also inactivation mechanisms to stop signals • We will learned about these with the cell cycle Comment

  29. Recognize several examples and importances of cell communication. • Identify the three stages of cell signaling. • Recognize how signals are received. • Recognize how signals are transduced. • Recognize the role of protein kinases and phosphorylation in signal amplification • Identify how cells respond to signals. • Recognize the role of cell signaling in apoptosis. Summary

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