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Cell Communication

Learn about cell signaling, types of communication, signal transduction pathways, and stages of cell signaling. Explore how animal cells communicate through various methods and the importance of response regulation.

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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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