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Cell Communication

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Cells communicate using various signaling pathways, enabling them to respond to stimuli. This process involves three main stages: reception, transduction, and response. Local regulators, such as animal growth factors and neurotransmitters, influence nearby cells, while hormones serve to relay information over longer distances. For instance, the Nobel Prize-winning work of Sutherland revealed how epinephrine triggers a response in liver and muscle cells, leading to glycogen breakdown for energy. Understanding these interactions is vital for exploring cellular functions across prokaryotes and eukaryotes.

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Cell Communication

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  1. Cell Communication

  2. What do cells say to each other? No Elizabeth! No… Don’t go! Life in the petri dish

  3. One type of cell “conversation” is sex

  4. Signal - Transduction Pathway • A mechanism linking a mechanical or chemical stimulus to a cellular response • yeast and mammals • bacteria and plants • prokaryotes and eukaryotes

  5. Communicating cells may be(close or far apart)

  6. Communicating cells may be(close or far apart)

  7. Local Regulator • A substance that influences cells in the vicinity • Examples: • animal growth factors; one cell can stimulate many nearby target cells (paracrine) • Animal nervous systems; neurotransmitter secretion into the synapse • Plants; cell wall is a problem (plasmodesmata) • Hormones; used by plants and animals

  8. Three stages of cell signaling • Reception • Transduction • Response

  9. Current understanding • Sutherland- Nobel Prize 1971 • Epinephrine stimulates cytosolic enzyme glycogen phosphorylase • In liver and muscle cells • Depolymerization of Glycogen • glucose-1-phosphate • glucose-6-phosphate • glycolysis (energy) • Alternately; strip the phosphate and release into the blood stream as glucose (fuel)

  10. Need intact cells for depolymerization • Epinephrine does not interact directly with enzyme responsible for breakdown • An intermediate step or steps inside cell • The plasma membrane is somehow involved in transmitting the signal • Sutherland’s work suggested: • At the receiving end; • Three stages • 1. Reception • 2. Transduction • 3. Response

  11. Direct Contact

  12. Overview of Cell Signaling

  13. Signal Reception

  14. A signal molecule binds to a receptor protein > protein changes shape • Signal molecule is complementary in shape to a specific site on the receptor • Acts like a ligand (small molecule that specifically binds to a larger one) • Conformation (shape) change directly activates the receptor to interact with another cellular molecule or • Causes the aggregation of two or more receptor molecules

  15. Most signal receptors are plasma - membrane proteins • Three major types: • G - protein • Tyrosine kinase • Ion - channel

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