Cell Signaling Mechanisms Quiz
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Questions and Answers

What is the primary role of intracellular cAMP in cell signaling?

  • To regulate homeostasis, such as salt and water levels (correct)
  • To regulate calcium levels
  • To inhibit protein synthesis
  • To increase intracellular calcium levels

    • What effect does Cholera Toxin have on GTP and GDP signaling?

  • It promotes GTP hydrolysis to GDP
  • It inhibits GTP to prevent cAMP production (correct)
  • It activates GDP to inhibit cAMP production
  • It facilitates the conversion of GTP to cAMP

    • What are the two types of second messengers generated by the activation of Phospholipase C?

  • DAG and IP3 (correct)
  • cAMP and IP3
  • PKC and DAG
  • cAMP and DAG

    • Which of the following responses is associated with the activation of Phospholipase C through Vasopressin?

    <p>Glycogen breakdown in the liver</p> Signup and view all the answers

    What is the key factor determining how a target cell responds to an extracellular signal?

    <p>The type of receptor present on the cell</p> Signup and view all the answers

    What is an example of a signal that acts over long distances in the body?

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

    What cellular mechanism does the neurotransmitter acetylcholine engage in cardiac tissue?

    <p>Inhibition of the heart rate</p> Signup and view all the answers

    Which of the following responses is NOT typically associated with the fight or flight response?

    <p>Increased digestion activity</p> Signup and view all the answers

    What is the primary role of Diacylglycerol (DAG) once generated?

    <p>Activates protein kinase C (PKC)</p> Signup and view all the answers

    Which type of drug mimics endogenous signals in GPCR signaling?

    <p>Receptor agonists</p> Signup and view all the answers

    How do cells typically respond to signals amidst the presence of multiple signals?

    <p>They respond to a limited number of specific signals.</p> Signup and view all the answers

    During a fight or flight response, which of the following occurs in the liver?

    <p>Glycogen breakdown to release glucose</p> Signup and view all the answers

    What factor critically influences how a target cell interprets a signal?

    <p>The specific receptor on the target cell</p> Signup and view all the answers

    Which of the following is a characteristic of short-distance signaling?

    <p>The signal acts locally between neighboring cells.</p> Signup and view all the answers

    In terms of signal molecules, which statement is true?

    <p>Signals can vary in size and chemical structure.</p> Signup and view all the answers

    What role does adrenaline play in cellular responses during the fight or flight response?

    <p>It generates multiple physical responses.</p> Signup and view all the answers

    What primarily determines how a cell will respond to a given signal?

    <p>The specific receptors and intracellular molecules present</p> Signup and view all the answers

    Which type of receptor allows ions to flow across the plasma membrane?

    <p>Ion channel receptors</p> Signup and view all the answers

    What is a characteristic of G-protein coupled receptors (GPCRs)?

    <p>They activate GTP-binding proteins when stimulated</p> Signup and view all the answers

    Which of the following is NOT a feature of cell surface receptors?

    <p>They are located on the inner membrane of the nucleus</p> Signup and view all the answers

    How do responses to signals differ in cells?

    <p>They can be fast or slow and may affect gene expression or protein function</p> Signup and view all the answers

    What is the role of extracellular signals in cellular signaling?

    <p>To be converted into intracellular signals</p> Signup and view all the answers

    Which of the following statements about receptors is accurate?

    <p>Different receptors can be activated by the same ligand</p> Signup and view all the answers

    Which type of receptor is expected to activate enzymes following ligand binding?

    <p>Enzyme-linked receptors</p> Signup and view all the answers

    What is the primary function of receptor antagonists?

    <p>Block receptor responses</p> Signup and view all the answers

    What allows GPCRs to activate associated G proteins?

    <p>Allosteric binding of ligand</p> Signup and view all the answers

    Which type of signaling allows for communication across long distances in the body?

    <p>Endocrine signaling</p> Signup and view all the answers

    What distinguishes extracellular receptors from intracellular receptors?

    <p>Extracellular receptors are located in the plasma membrane</p> Signup and view all the answers

    How do signals vary in their reach and effectiveness?

    <p>Signals differ in size and chemical structure</p> Signup and view all the answers

    Which statement about ligands and receptor binding is correct?

    <p>Specificity of receptors is crucial for signal transduction</p> Signup and view all the answers

    What type of signaling molecules can be classified as intracellular?

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

    What is a common characteristic of all signaling molecules?

    <p>They can act both extracellularly and intracellularly</p> Signup and view all the answers

    What is the primary function of receptor tyrosine kinases (RTKs)?

    <p>They activate intracellular signaling molecules through phosphorylation.</p> Signup and view all the answers

    How many human receptor tyrosine kinases are identified?

    <p>60</p> Signup and view all the answers

    What type of receptors can activate enzyme-coupled receptors?

    <p>Receptors can either be enzymes themselves or associate with enzymes.</p> Signup and view all the answers

    What is the role of autotransphosphorylation in RTK activation?

    <p>It helps in the formation of intracellular complexes.</p> Signup and view all the answers

    What feature is common to all receptor tyrosine kinases?

    <p>They possess a ligand-binding region in the extracellular space.</p> Signup and view all the answers

    Which statement about RTKs being molecular switches is true?

    <p>They toggle between active and inactive states.</p> Signup and view all the answers

    What type of responses can cell signaling result in?

    <p>Responses in the cytosol that are fast and/or in the nucleus that are slower</p> Signup and view all the answers

    What did Robert Lefkowitz and Brian Kobilka discover that earned them the Nobel Prize in Chemistry?

    <p>Inner workings of G-protein–coupled receptors</p> Signup and view all the answers

    What is the significance of the single membrane spanning alpha-helical domain in RTKs?

    <p>It anchors the RTK within the membrane.</p> Signup and view all the answers

    Which Nobel Prize was awarded for the discovery related to signal transduction in the nervous system?

    <p>The 2000 Nobel Prize in Physiology or Medicine</p> Signup and view all the answers

    Enzyme-coupled receptors are primarily activated by?

    <p>The binding of a ligand.</p> Signup and view all the answers

    What is one characteristic of molecular switches in cell signaling?

    <p>They help fine-tune responses at various control points</p> Signup and view all the answers

    Which of the following scientists contributed to the understanding of how cells sense oxygen, leading to a Nobel Prize in Medicine?

    <p>Peter Ratcliffe</p> Signup and view all the answers

    Study Notes

    Lecture Information

    • Lecture materials cover basic principles of cell biology, focusing on cell communication and signalling.
    • Lecture 1 focused on principles of cell communication and steroid receptor signalling.
    • Lecture 2 focused on ion channel and G-coupled protein receptor signalling.
    • Lecture 3 focused on enzyme-coupled receptors.
    • Lecture 4 focused on cell signalling in disease, specifically diabetes.

    Cell Communication and Signalling

    • Cell signalling involves four key steps: receive, recognise, relay, and respond.
    • Cell signalling is crucial for coordinating cell functions, responding to environmental changes, maintaining homeostasis, and cell development and survival.
    • Different types of cell signalling exist: autocrine, paracrine, juxtacrine, endocrine, and neuronal.
    • Autocrine signalling involves releasing molecules that act upon the cell that produced them.
    • Paracrine signalling involves releasing molecules that act upon nearby cells.
    • Juxtacrine signalling involves direct contact between adjacent cells.
    • Endocrine signalling involves hormones traveling through the bloodstream to target cells.
    • Neuronal signalling involves transmitting signals through electrical and chemical impulses.

    Cell signalling in disease - Diabetes

    • Glucose homeostasis is tightly regulated in health by multiple hormones, including insulin and glucagon.
    • Diabetes is a disorder of glucose homeostasis.
    • Type 1 diabetes usually results from autoimmune destruction of insulin-producing beta cells.
    • Type 2 diabetes arises from a combination of insulin resistance and inadequate insulin secretion.
    • Insulin, produced in the pancreas islets of Langerhans, lowers blood glucose while glucagon raises levels through glycogen breakdown in the liver.

    Key Receptors

    • Ligand-gated ion channels are transmembrane proteins that open or close in response to specific ligands causing ion flow into and out of the cell.
    • G-protein coupled receptors (GPCRs) are a large family of membrane-bound proteins, involved in a vast array of cellular processes, and are an important target for drugs.
    • Enzyme-coupled receptors, such as receptor tyrosine kinases (RTKs) or JAK-STAT are membrane glycoproteins whose binding to specific ligands results in the activation of cytoplasmic signaling cascades.
    • Different cell types have diverse responses to the same signal due to different intracellular pathways being activated.
    • Insulin receptor (IR), is an enzyme-coupled receptor that regulates glucose uptake and glycogen synthesis.

    Treatment of Diabetes Mellitus

    • Current treatment approaches include insulin replacement (type 1 diabetes) or lifestyle modifications and/or pharmacological agents (type 2 diabetes).

    Stem Cell Therapies in Diabetes

    • Stem-based approaches to diabetes involve generating insulin-producing beta cells from stem cells.
    • Current stem cell therapies such as VX-880 and VX-264 are in clinical trials.
    • The use of stem cells to generate stem cell-derived islets might overcome problems associated with traditional treatments and address complications.

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    Description

    Test your knowledge on the mechanisms and roles of cell signaling, focusing on key concepts such as cAMP, cholera toxin effects, and second messengers. This quiz covers essential topics related to G protein-coupled receptors and the physiological responses they mediate.

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