Cellular Signaling and Communication Quiz
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Questions and Answers

What is primarily responsible for the specificity in synaptic signaling?

  • The speed of signal delivery
  • The type of neurotransmitter released
  • The presence of gap junctions
  • The synaptic contacts between a nerve cell and target cells (correct)

    • Which type of cellular response is likely to occur more quickly?

  • Alterations in cell movement or secretion (correct)
  • Changes in gene transcription
  • Synthesis of new proteins
  • Increased cell growth and division

    • What do gap junctions allow for between neighboring cells?

  • Communication through macromolecules
  • Direct exchange of inorganic ions and small water-soluble molecules (correct)
  • Synthesis of new proteins
  • Phosphorylation of effector proteins

    • What is a consequence of synaptic changes mediated by alterations in membrane potential?

    <p>They generally require gene expression changes</p> Signup and view all the answers

    Which characteristic distinguishes paracrine signaling from synaptic signaling?

    <p>Paracrine signals act on nearby cells whereas synaptic signaling is targeted.</p> Signup and view all the answers

    What role do extracellular signal molecules play in cell survival?

    <p>They must be present in appropriate combinations for survival.</p> Signup and view all the answers

    How does acetylcholine function differently in various cell types?

    <p>Different receptors or intracellular responses lead to varied effects.</p> Signup and view all the answers

    What kind of molecules cannot pass through gap junctions?

    <p>Macromolecules such as proteins and nucleic acids</p> Signup and view all the answers

    What primarily influences the speed of response to an extracellular signal in target cells?

    <p>The mechanism of signal delivery and the nature of the target response</p> Signup and view all the answers

    What defines a morphogen in cellular signaling during development?

    <p>It creates a concentration gradient that influences gene expression.</p> Signup and view all the answers

    What happens to a cell deprived of appropriate survival signals?

    <p>It triggers a form of programmed cell death.</p> Signup and view all the answers

    What type of signaling mechanism provides for the most intimate cellular communication?

    <p>Gap junctions</p> Signup and view all the answers

    In terms of cellular response to signals, what factor besides receptor type affects how a cell responds?

    <p>The cell's intracellular machinery.</p> Signup and view all the answers

    Why might two cells with the same receptor protein respond to a signal differently?

    <p>The presence of additional signaling pathways that alter interpretation.</p> Signup and view all the answers

    What is the significance of signal molecule combinations in cellular functions?

    <p>Different combinations can either promote or inhibit specific cell behaviors.</p> Signup and view all the answers

    What is a characteristic feature of cells during developmental stages regarding their responses to signals?

    <p>Their fate is influenced by the concentration of extracellular signals.</p> Signup and view all the answers

    What is a common structural characteristic of all GPCRs?

    <p>They form a single polypeptide chain that spans the membrane seven times.</p> Signup and view all the answers

    Which of the following signal molecules is known to activate multiple GPCRs?

    <p>Serotonin</p> Signup and view all the answers

    What happens to the alpha subunit of the G protein upon GPCR activation?

    <p>It releases GDP and binds GTP.</p> Signup and view all the answers

    How many G protein subunits are there, and what is their composition?

    <p>Three subunits composed of alpha, beta, and gamma.</p> Signup and view all the answers

    In which state is the G protein considered inactive?

    <p>When the alpha subunit has GDP bound.</p> Signup and view all the answers

    What occurs after the alpha subunit of the G protein hydrolyzes its bound GTP?

    <p>It becomes inactive and binds GDP again.</p> Signup and view all the answers

    Which of the following best describes the role of G proteins in GPCR signaling?

    <p>They relay signals into the cell by coupling with receptors.</p> Signup and view all the answers

    Which type of molecules can act on GPCRs based on their structural variety?

    <p>Proteins, small peptides, amino acid derivatives, fatty acid derivatives, and photons.</p> Signup and view all the answers

    What distinguishes long-distance signaling from local signaling between cells?

    <p>Long-distance signaling utilizes extracellular signal molecules that travel through extracellular space.</p> Signup and view all the answers

    Which of the following molecules is NOT typically involved in cell signaling?

    <p>Carbohydrates</p> Signup and view all the answers

    How are receptors initially activated when a signaling molecule binds to them?

    <p>They undergo a conformational change.</p> Signup and view all the answers

    What type of proteins can be considered as targets for intracellular signaling pathways?

    <p>Effector proteins that alter cell behavior.</p> Signup and view all the answers

    What mechanism can certain signal molecules use to affect target cells without being released?

    <p>Attachment to the surface of the signaling cell.</p> Signup and view all the answers

    What role do intracellular signaling proteins generally play in the signaling process?

    <p>They relay the signal and activate intracellular targets.</p> Signup and view all the answers

    Which of the following options describes a characteristic of signal molecules in multicellular organisms?

    <p>They include a variety of types like steroids and gases.</p> Signup and view all the answers

    Which of the following statements about receptor proteins is true?

    <p>Receptor proteins bind to specific signal molecules to initiate a response.</p> Signup and view all the answers

    What effect does acetylcholine released by a nerve have on heart muscle cell contraction?

    <p>It reduces both the rate and strength of contraction.</p> Signup and view all the answers

    Which G protein is directly involved in inhibiting adenylyl cyclase in heart muscle cells?

    <p>Gi</p> Signup and view all the answers

    What role does the βɣ subunit of Gi play in heart muscle cell signaling?

    <p>It opens K+ channels in the plasma membrane.</p> Signup and view all the answers

    What initiates the desensitization of GPCRs when exposed to prolonged stimulation?

    <p>Phosphorylation by GPCR kinases.</p> Signup and view all the answers

    What is a key characteristic that differentiates enzyme-coupled receptors from GPCRs?

    <p>Enzyme-coupled receptors have intrinsic enzyme activity or associate directly with an enzyme.</p> Signup and view all the answers

    Which of the following best describes the function of receptor tyrosine kinases?

    <p>They directly phosphorylate specific tyrosines on themselves and other signaling proteins.</p> Signup and view all the answers

    What is the primary consequence of binding an arrestin to a phosphorylated GPCR?

    <p>It directs the receptor toward endocytosis and inhibits G protein binding.</p> Signup and view all the answers

    Which of the following is NOT a principal class of enzyme-coupled receptors?

    <p>G-protein coupled receptors</p> Signup and view all the answers

    What is the role of CREB once it is phosphorylated by PKA?

    <p>It recruits CREB-binding protein (CBP).</p> Signup and view all the answers

    Which signaling pathway directly induces the release of Ca2+ from the endoplasmic reticulum?

    <p>The inositol phospholipid signaling pathway.</p> Signup and view all the answers

    What are the two products generated when PI(4,5)P2 is hydrolyzed by activated PLCβ?

    <p>IP3 and diacylglycerol.</p> Signup and view all the answers

    Which of the following describes the mechanism by which diacylglycerol activates protein kinase C (PKC)?

    <p>It recruits PKC to the cytosolic face of the plasma membrane.</p> Signup and view all the answers

    What activates phospholipase C-β in the inositol phospholipid signaling pathway?

    <p>Gq protein.</p> Signup and view all the answers

    The family of kinases that phosphorylate proteins in response to calcium binding is known as what?

    <p>Ca2+/calmodulin-dependent kinases.</p> Signup and view all the answers

    What is the main function of inositol 1,4,5-trisphosphate (IP3) in cell signaling?

    <p>To release Ca2+ from the endoplasmic reticulum.</p> Signup and view all the answers

    Which of the following correctly describes how CREB is influenced by calcium signaling?

    <p>Calcium activates CaM-kinases that phosphorylate CREB.</p> Signup and view all the answers

    Study Notes

    Cell Communication and Signaling

    • Communication between cells is primarily mediated by extracellular signal molecules.
    • Some signals act over long distances, others only to nearby cells.
    • Multicellular organisms often emit and receive signals.
    • Signal reception relies on receptor proteins, typically found on the cell surface, binding to signal molecules.
    • Receptor activation triggers intracellular signaling pathways.
    • Intracellular signaling proteins relay and process the signal within the cell.
    • Effector proteins are altered by the activated signaling pathway to change cell behavior.
    • Effectors can be gene regulatory proteins, ion channels, components of metabolic pathways, or parts of the cytoskeleton.
    • Signals can act over long or short distances.

    Types of Intercellular Signaling

    • Contact-dependent: Cells in direct contact.
    • Paracrine: Signals released into the extracellular space affect nearby cells.
    • Synaptic: Neurons release neurotransmitters at synapses, commonly on distant cells.
    • Endocrine: Hormones are released into the bloodstream for distribution throughout the body.

    Cellular Responses to Signals

    • Each cell type has a specific receptor set.
    • Signaling molecules act in combinations to regulate cellular behavior.
    • Cells need multiple signals to survive, divide, or differentiate.
    • Cells can undergo apoptosis in response to a lack of survival signals.

    Intracellular Signaling Proteins

    • Many signaling proteins act as molecular switches.
    • Switches are toggled in two main ways:
    • Phosphorylation, either activating or deactivating the protein.
    • GTP binding proteins, that become active when GTP is acquired and inactive when it's converted to GDP.

    Cellular Responses to Signals

    • Cells respond uniquely to the same signal.
    • Reception, intracellular processing, and the response mechanism differ in each cell type.

    Other Mechanisms of Intracellular Signaling

    • Gap junctions: Direct cytoplasmic channels between adjacent cells, enabling the coordinated exchange of small messenger molecules..

    Cell Signaling Mechanisms for Long-Range Signaling

    • Endocrine signaling relies on hormones transported throughout the bloodstream to reach distant target cells with specific receptors.
    • Neuronal signal, or synaptic signaling, utilizes neurotransmitters released at synapses to locally affect target cells in a highly specific way.

    Speed of Cellular Responses

    • The speed of the response to an extracellular signal is influenced by the signaling cascade's nature and the target cell's response mechanism;
    • Rapid responses often involve changes in existing proteins, while slower responses may involve changes in gene expression.

    Intracellular signaling pathways

    • Intracellular signaling pathways can be complex and involve numerous steps.
    • Signaling cascades can be activated, amplified, and modulated by several factors.

    GPCR Activation and cAMP Production

    • Some G proteins regulate the production of cyclic AMP (cAMP) by activating adenylyl cyclase, affecting cAMP concentration.

    GPCR Activation and Inositol Phospholipid Signaling

    • Some G proteins activate phospholipase C-β and initiate a signaling pathway involving inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG), which influences intracellular calcium levels and activates protein kinase C (PKC).

    GPCR Activation and Ion Channel Regulation

    • Some G proteins directly regulate ion channels in the plasma membrane, changing ion permeability and altering cell excitability.

    GPCR Desensitization

    • Prolonged exposure to high ligand concentrations causes desensitization or adaptation in several ways.
    • Receptor phosphorylation plays a crucial role; it triggers dissociation of G-protein from GPCR and sometimes receptor internalization.

    Receptor Tyrosine Kinases (RTKs)

    • RTKs are transmembrane receptors that, when activated, phosphorylate themselves and other proteins, initiating downstream signaling.
    • Ligand binding and subsequent receptor dimerization activate intracellular tyrosine kinase activity.
    • Phosphorylated tyrosines on the activated receptors serve as docking sites for signaling proteins possessing SH2 or PTB domains.

    PI 3-Kinase Activity

    • PI 3-kinase is another docking protein that can bind to activated RTKs.
    • It creates specific docking sites.

    Tyrosine Kinase-Associated Receptors

    • The cytokine receptor family is the most prominent family of tyrosine kinase-associated receptors;
    • Activation is achieved by specific protein and specific intracellular signaling molecules

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    Cell Communication and Signaling PDF

    Description

    Test your knowledge on various aspects of cellular signaling and communication mechanisms. This quiz covers synaptic signaling, paracrine signaling, and the role of extracellular signal molecules. Understand the intricacies of how cells communicate and the consequences of these signaling pathways.

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