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Cell Communication in General Biology

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Termini in questo insieme (20)

  • What are the three main modes of cell communication?
    Direct contact, local signaling, and endocrine (hormonal) signaling.
  • What are gap junctions and plasmodesmata?
    Structures that allow direct exchange of molecules between adjacent cells in animals (gap junctions) and plants (plasmodesmata).
  • What is the general sequence of cell signaling?
    Signal reception → signal transduction → cellular response.
  • How do lipid-soluble hormones signal cells?
    They cross the membrane and bind to intracellular receptors.
  • How do lipid-insoluble hormones signal cells?
    They bind to cell-surface receptors because they cannot cross the membrane.
  • What is signal amplification in cell communication?
    One signaling molecule activates many downstream molecules, greatly increasing the cellular response.
  • Describe the role of G-protein coupled receptors (GPCRs) in signaling.
    GPCRs activate G proteins, which then activate enzymes like adenylyl cyclase to produce second messengers.
  • What is a second messenger? Give an example.
    A small, water-soluble molecule that diffuses rapidly inside cells to propagate signals; example: cAMP.
  • How does cAMP function in GPCR signaling?
    cAMP activates protein kinase A (PKA), which triggers cellular responses such as glycogen breakdown.
  • What determines the specific cellular response to a hormone?
    The type of receptor expressed and the cell's signaling pathways.
  • What are the two major types of cellular responses to signals?
    1) Modification of existing proteins (rapid), 2) Changes in gene expression (slower).
  • How do receptor tyrosine kinases (RTKs) work?
    Ligand binding causes dimerization and autophosphorylation, activating signaling pathways for cell growth and division.
  • What is the role of Ras in RTK signaling?
    Ras is activated by RTKs and triggers a phosphorylation cascade to amplify the signal.
  • What is the function of kinases and phosphatases in signaling?
    Kinases add phosphate groups to activate proteins; phosphatases remove them to deactivate proteins.
  • How do ligand-gated ion channels function in cell signaling?
    Ligand binding opens the channel, allowing ions to flow and rapidly convert chemical signals into electrical responses.
  • Where are intracellular receptors located and what do they do?
    In the cytoplasm or nucleus; they bind small or hydrophobic hormones and act as transcription factors.
  • What triggers apoptosis in cells?
    External death signals or internal damage activate caspases that dismantle the cell safely.
  • Why is apoptosis important?
    It removes damaged or infected cells, prevents tissue damage, and shapes development.
  • How do insulin and glucagon regulate blood glucose?
    Insulin lowers blood glucose by promoting uptake and storage; glucagon raises glucose by stimulating release from the liver.
  • Why is signal termination important in hormonal signaling?
    It prevents over-correction and maintains homeostasis by turning off signals when no longer needed.