Cell Communication 3
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Questions and Answers

What is the main role of G protein βꝩ subunits in cellular signaling?

  • Promote signal amplification (correct)
  • Directly activate receptor tyrosine kinases
  • Inhibit second messenger production
  • Enhance intracellular receptor transduction

    • In the GPCR-PIP2 pathway, which second messenger is associated with it?

  • DAG (correct)
  • cGMP
  • Glutamate
  • Ketamine

    • What is the main function of Receptor Tyrosine Kinases (RTKs) in cellular signaling?

  • Activate cAMP production
  • Amplify calcium signals
  • Inhibit gated ion channels
  • Transduce signals by phosphorylating tyrosine residues (correct)

    • Which type of receptors are gated ion channels (ionotropic receptors)?

    <p>Ligand-gated ion channels</p> Signup and view all the answers

    What is the process described as receptor mediated endocytosis?

    <p>Cellular uptake of ligand-receptor complexes for signaling molecule degradation</p> Signup and view all the answers

    What is the function of diacylglycerol (DAG) in cellular response to signal hormone binding?

    <p>Activates Protein Kinase C (PKC)</p> Signup and view all the answers

    Which second messenger diffuses to the endoplasmic reticulum (ER) and opens specific Ca2+ channels upon hormone binding?

    <p>Inositol 1,4,5-trisphosphate (IP3)</p> Signup and view all the answers

    How do rises in intracellular [Ca2+] affect cellular responses like contraction in muscles?

    <p>Stimulate cross-bridge cycling in muscles</p> Signup and view all the answers

    What regulates the activity of many Ca2+-dependent enzymes/proteins by binding to Ca2+ at a certain threshold?

    <p>Calmodulin (CaM)</p> Signup and view all the answers

    What is the role of kinases in cellular pathways according to the text?

    <p>Phosphorylation of proteins via covalent bonds</p> Signup and view all the answers

    Which enzyme is activated by rises in intracellular [Ca2+] and subsequently stimulates cross-bridge cycling?

    <p>Myosin light chain kinase</p> Signup and view all the answers

    What activates Protein Kinase A (PKA) according to the text?

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

    Which molecule can move into the nucleus and phosphorylate CREB?

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

    How is Ca++ release triggered in the cell according to the text?

    <p>PKA activation</p> Signup and view all the answers

    Which G protein subunit directly activates or inactivates ion channels in the plasma membrane?

    <p>β subunit</p> Signup and view all the answers

    What specific membrane phospholipid is targeted by phospholipase C (PLC)?

    <p>PIP2</p> Signup and view all the answers

    What physiological effect can be expected from GPCRs coupled to Gq proteins?

    <p>Stimulated smooth muscle contraction</p> Signup and view all the answers

    What type of receptor is the Nicotinic acetylcholine (ACh) receptor?

    <p>Ligand-gated ion channel</p> Signup and view all the answers

    Where do lipophilic signals carried by transport proteins in the blood plasma bind?

    <p>Intracellular receptors in the cytoplasm or nucleus</p> Signup and view all the answers

    Which type of hormones bind to intracellular receptors that are transcription regulators?

    <p>Steroid hormones</p> Signup and view all the answers

    What is essential for receptor-mediated endocytosis initiation?

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

    What does the binding of ligands to intracellular receptor proteins alter?

    <p>The ability of these proteins to control gene transcription</p> Signup and view all the answers

    What is the main outcome of the signal mediated by the Nicotinic acetylcholine (ACh) receptor?

    <p>Depolarization of membrane triggering muscle contraction</p> Signup and view all the answers

    What is the main difference between Serine/Threonine Kinases and Tyrosine Kinases?

    <p>Serine/Threonine Kinases phosphorylate serine and threonine amino acids, while Tyrosine Kinases phosphorylate tyrosine amino acids.</p> Signup and view all the answers

    How do Receptor Tyrosine Kinases (RTKs) transduce extracellular signals differently from G Protein-Coupled Receptors (GPCRs)?

    <p>RTKs autophosphorylate, while GPCRs rely on ligand binding for activation.</p> Signup and view all the answers

    What is a major regulatory mechanism for the Insulin Receptor?

    <p>Receptor sequestration and downregulation.</p> Signup and view all the answers

    What is the main function of excitable cells in response to external signals?

    <p>Regulate muscle contraction.</p> Signup and view all the answers

    How are ion channels in excitable cells activated?

    <p>By binding of specific ligands.</p> Signup and view all the answers

    Which type of receptors can modulate the phosphorylation state and be regulated by antagonist drugs?

    <p>Tyrosine Kinases</p> Signup and view all the answers

    What is the main function of G protein βꝩ subunits in cellular signaling?

    <p>Inhibiting the activity of adenylate cyclase</p> Signup and view all the answers

    Which second messenger is associated with the GPCR-PIP2 pathway?

    <p>Diacylglycerol (DAG)</p> Signup and view all the answers

    What is the mechanism of action of Receptor Tyrosine Kinases (RTKs) in cellular signaling?

    <p>Activating downstream signaling pathways</p> Signup and view all the answers

    What is the role of gated ion channels (ionotropic receptors) in cellular communication?

    <p>Directly activate intracellular signaling cascades</p> Signup and view all the answers

    How do different second messengers like cAMP, Ca+2, DAG, and IP3 affect cellular responses?

    <p>Activate different downstream pathways</p> Signup and view all the answers

    What type of signal molecules bind to intracellular receptors that are transcription regulators?

    <p>Steroid hormones</p> Signup and view all the answers

    Which protein is essential for the initiation of receptor-mediated endocytosis?

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

    What is the main function of intracellular receptors described in the text?

    <p>Control gene transcription</p> Signup and view all the answers

    Which type of receptor is the Nicotinic acetylcholine (ACh) receptor based on its function?

    <p>Ligand-gated ion channel</p> Signup and view all the answers

    What is the role of membrane-associated protein Clathrin in cellular signaling pathways?

    <p>Mediating endocytosis</p> Signup and view all the answers

    How do small hydrophobic signal molecules enter target cells?

    <p>Diffusing directly across the plasma membrane</p> Signup and view all the answers

    What effect does the rise in intracellular [Ca2+] have on Calmodulin (CaM)?

    <p>Ca2+ activates Calmodulin by causing a conformational change</p> Signup and view all the answers

    How is Protein Kinase C (PKC) activated in combination with DAG?

    <p>Increase in intracellular [Ca2+]</p> Signup and view all the answers

    What is the role of Calmodulin-dependent kinases?

    <p>Activate enzymes upon Ca2+ binding</p> Signup and view all the answers

    How are rises in intracellular [Ca2+] handled in excitable cells?

    <p>Stimulate cross-bridge cycling in muscles</p> Signup and view all the answers

    What triggers the release of stored Ca2+ to the cytosol from the ER?

    <p>[Ca2+] increase in the cytosol</p> Signup and view all the answers

    How does IP3 affect the endoplasmic reticulum (ER) upon binding?

    <p>Opens specific Ca2+ channels</p> Signup and view all the answers

    What is the main difference between Serine/Threonine Kinases and Tyrosine Kinases?

    <p>Serine/Threonine Kinases phosphorylate serine and threonine amino acid residues, while Tyrosine Kinases phosphorylate proteins on tyrosine residues.</p> Signup and view all the answers

    What is the primary function of Protein Kinase A (PKA) as described in the text?

    <p>Activates enzymes involved in fat mobilization</p> Signup and view all the answers

    What is the major regulatory mechanism for the Insulin Receptor?

    <p>Receptor sequestration and downregulation</p> Signup and view all the answers

    Which molecule can move into the nucleus to phosphorylate CREB?

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

    In excitable cells, what determines their excitability?

    <p>Change in transmembrane electrical potential (voltage) or binding of specific ligands</p> Signup and view all the answers

    How is Ca++ release triggered in the cell according to the text?

    <p>By activation of phospholipase C (PLC)</p> Signup and view all the answers

    Which type of receptors can be modulated by antagonist drugs and regulate the phosphorylation state?

    <p>Receptor Tyrosine Kinases</p> Signup and view all the answers

    What is the specific role of G proteins in cellular signaling, as mentioned in the text?

    <p>Activate or inactivate ion channels in the plasma membrane</p> Signup and view all the answers

    What transduces extracellular signals differently between Receptor Tyrosine Kinases (RTKs) and G Protein-Coupled Receptors (GPCRs)?

    <p>Mechanism of signal transduction</p> Signup and view all the answers

    What is the main second messenger associated with the GPCR-Gq protein pathway?

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

    What is the key feature that distinguishes Tyrosine Kinases from Serine/Threonine Kinases?

    <p>Phosphorylation specificity</p> Signup and view all the answers

    What distinguishes Serine/Threonine Kinases from Tyrosine Kinases?

    <p>The amino acids they phosphorylate in their targets</p> Signup and view all the answers

    How do Receptor Tyrosine Kinases (RTKs) transduce extracellular signals differently from G Protein-Coupled Receptors (GPCRs)?

    <p>Through a different mechanism of signal transduction</p> Signup and view all the answers

    What is a major regulatory mechanism for Receptor Tyrosine Kinases (RTKs) apart from receptor sequestration and downregulation?

    <p>Modulation of the phosphorylation state</p> Signup and view all the answers

    What is the primary feature that allows certain excitable cells to respond to external signals?

    <p>Change in membrane potential using ion channels</p> Signup and view all the answers

    What is the main regulatory mechanism for the Insulin Receptor specifically?

    <p>Receptor endocytosis and degradation</p> Signup and view all the answers

    What is the primary function of ligand-gated ion channels in excitable cells?

    <p>Serving as a regulated path for movement of ions</p> Signup and view all the answers

    What is the primary function of Protein Kinase A (PKA) in cellular signaling?

    <p>Phosphorylation of CREB leading to altered gene expression</p> Signup and view all the answers

    How is calcium release triggered in the cell according to the provided information?

    <p>Through the cAMP pathway and activation of PKA</p> Signup and view all the answers

    What can move into the nucleus and phosphorylate CREB?

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

    What is the specific membrane phospholipid targeted by phospholipase C (PLC)?

    <p>PIP2</p> Signup and view all the answers

    Which outcome is associated with G proteins coupled to Gq proteins?

    <p>Activation of phospholipase C (PLC)</p> Signup and view all the answers

    What is the result of ligand-gated ion channel activation by G protein βꝩ subunits?

    <p>Depolarization of cells made easier</p> Signup and view all the answers

    What is the primary function of cAMP in cellular signaling pathways?

    <p>Serving as a second messenger for several regulatory molecules</p> Signup and view all the answers

    Which signaling pathway involves G protein βꝩ subunits?

    <p>GPCR cAMP pathway</p> Signup and view all the answers

    How do Receptor Tyrosine Kinases (RTKs) differ from G Protein-Coupled Receptors (GPCRs) in signal transduction?

    <p>RTKs directly phosphorylate proteins, while GPCRs activate G proteins</p> Signup and view all the answers

    In cellular signaling, what is the mechanism of action of intracellular receptors?

    <p>Directly regulating gene transcription after ligand binding</p> Signup and view all the answers

    What is the role of receptor-mediated endocytosis in cellular communication?

    <p>Recycling of membrane receptors and ligand internalization</p> Signup and view all the answers

    What is the main function of the Nicotinic acetylcholine (ACh) receptor?

    <p>Triggers depolarization of the membrane</p> Signup and view all the answers

    How do lipophilic signal molecules typically enter target cells?

    <p>Through direct diffusion across the plasma membrane</p> Signup and view all the answers

    What is the role of Clathrin in receptor-mediated endocytosis?

    <p>Essential protein for endocytosis initiation</p> Signup and view all the answers

    Which type of receptors are transcription regulators in the cytoplasm or nucleus?

    <p>Intracellular receptors</p> Signup and view all the answers

    What happens when ligands bind to intracellular receptor proteins?

    <p>They regulate specific gene expression</p> Signup and view all the answers

    Which molecule is responsible for mediating the passage of an electrical signal at some synapses?

    <p>Nicotinic acetylcholine (ACh)</p> Signup and view all the answers

    What is the role of IP3 in cellular signaling after binding to specific IP3-gated Ca2+ channels?

    <p>Induces the release of stored Ca2+ from the endoplasmic reticulum (ER)</p> Signup and view all the answers

    What is the main function of Calmodulin (CaM) in response to changes in intracellular [Ca2+] levels?

    <p>Regulates Ca2+-dependent enzymes/proteins</p> Signup and view all the answers

    In cellular signaling, what is the primary function of kinases?

    <p>Phosphorylate proteins via covalent bonds</p> Signup and view all the answers

    What effect does a rise in intracellular [Ca2+] levels have on Calmodulin (CaM)?

    <p>Triggers a conformational change and binding to target proteins</p> Signup and view all the answers

    Which process involves functional changes in target proteins like enzyme activity, cellular location, and association with other proteins?

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

    What is the role of Gq protein activation in the GPCR-PIP2 pathway?

    <p>Increases cytosolic [Ca2+] levels</p> Signup and view all the answers

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