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Cell Communication

Cell Communication. CHAPTER 11. An Example of Cell Communication: Fight or Flight Response. http://learn.genetics.utah.edu/content/begin/cells/cellcom/. Cell Signaling. Animal cells communicate by: Direct contact (gap junctions) Secreting local regulators (growth factors, neurotransmitters)

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Cell Communication

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  1. Cell Communication CHAPTER 11

  2. An Example of Cell Communication: Fight or Flight Response http://learn.genetics.utah.edu/content/begin/cells/cellcom/

  3. Cell Signaling Animal cells communicate by: • Direct contact (gap junctions) • Secreting local regulators (growth factors, neurotransmitters) • Long distance (hormones) • Chemical and Electrical signals

  4. Types of Communication: • Autocrine- receptor on same cell (growth factors telling tumor cells to keep growing) • Paracrine- neighboring cell is near signal releasing cell (two neurons) • Juxtacrine- target and releasing cells are in physical contact (quorum sensing in bacteria, gap junctions) • - Endocrine- chemicals that need to travel long distances (hormones)

  5. Signal Transduction Pathway • Series of steps by which a signal on a cell’s surface is converted to a specific cellular response • Signaling can be short distance or long distance

  6. 3 Stages of Cell Signaling: • Reception: A signal molecule (ligand) binds to a receptor protein causing it to change shape • Transduction: series of molecules interactions that relay signal from receptor to target molecule • Response: regulation of transcription or cytoplasmic activities

  7. 1. Reception • Binding between signal molecule (ligand) + receptor is highly specific. • Receptors found in: • Intracellular receptors(cytoplasm, nucleus) • hydrophobic ligands • Eg. testosterone or other hormones turning on and off certain genes • Plasma membrane receptor • water-soluble ligands

  8. G-Protein-Coupled Receptor https://www.youtube.com/watch?v=xT0mAQ4726s 2 min

  9. Tyrosine Receptor Kinase https://www.youtube.com/watch?v=kiHAdan2AOY 1 min

  10. Ligand-Gated Ion Channel http://www.youtube.com/watch?v=A1sdk7hyGz8 2 minutes

  11. Plasma Membrane Receptors

  12. 2. Transduction • Cascades of molecular interactions relay signals from receptors  target molecules; “dominoes effect” • Protein kinase: enzyme that phosphorylates and activates proteins at next level • Phosphorylation cascade: enhance and amplify signal

  13. Second Messengers • small, nonprotein molecules/ions that can relay signal inside cell • Eg. cyclic AMP (cAMP) and Ca2+ - cAMP is made when adenylcyclaseconverts ATP to cAMP - cAMP activates protein kinase A which phosphorylates other proteins

  14. 3. Response • Regulate protein synthesis by turning on/off genes in nucleus (gene expression) • Regulate activity of proteins in cytoplasm

  15. G-Protein-coupled Receptors Figure 6-11: The G protein-coupled adenylyl cyclase-cAMP system

  16. Transduction Reviewed Figure 6-14: Summary of signal transduction systems

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