Cell Signaling Mechanisms Quiz
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Questions and Answers

What does GTP stand for?

Guanosine triphosphate

What is cAMP a short form of?

Cyclic Adenosine Monophosphate

What is the role of adenylyl cyclase in the cAMP signaling pathway?

  • It converts ATP to cAMP. (correct)
  • It binds to the signal molecule.
  • It acts as a second messenger.
  • It activates protein kinase A.
  • Protein kinase A (PKA) is inactive in the presence of cAMP.

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

    What is the role of the activated G protein in the cAMP signaling pathway?

    <p>The activated G protein binds to and activates adenylyl cyclase.</p> Signup and view all the answers

    What is the role of inositol 1,4,5-trisphosphate (IP3) in the PLC/PKC signaling pathway?

    <p>IP3 binds to receptors on the endoplasmic reticulum, causing the release of calcium ions (Ca2+) into the cytosol.</p> Signup and view all the answers

    What is the role of diacylglycerol (DAG) in the PLC/PKC signaling pathway?

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

    What is the role of the activated PKC in the PLC/PKC signaling pathway?

    <p>Activated PKC phosphorylates a variety of target proteins, leading to a range of cellular effects.</p> Signup and view all the answers

    What is Calmodulin?

    <p>Calmodulin is a small, calcium-binding protein that acts as a messenger in a variety of cellular processes.</p> Signup and view all the answers

    What is the role of calcium in cellular signaling?

    <p>Calcium acts as a second messenger, triggering a variety of cellular responses, including muscle contraction, neurotransmitter release, and gene expression.</p> Signup and view all the answers

    Calcium transients can only be triggered by GPCRs

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

    Calcium waves are often a result of positive feedback loops.

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

    How do calcium waves propagate through feedback?

    <p>When calcium is released from the endoplasmic reticulum, it activates IP3 receptors which release more calcium, setting off a chain reaction</p> Signup and view all the answers

    The activation of phospholipase C-beta can lead to the activation of protein kinase C.

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

    What is the name of the protein that can activate Protein Kinase C?

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

    Inositol 1,4,5-trisphosphate (IP3) is a second messenger that is involved in the release of calcium from the endoplasmic reticulum.

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

    The JAK/STAT pathway is a signaling pathway that is activated by cytokines and involves phosphorylation events.

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

    The JAK/STAT pathway is part of the 'cross-talk' of the signal transduction pathways.

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

    Study Notes

    Cell Signaling (Continued)

    • Cyclic AMP (cAMP) activation through GPCRs involves a cascade: A signal molecule activates a G protein-coupled receptor (GPCR), which activates adenylyl cyclase. Adenylyl cyclase converts ATP to cAMP. cAMP activates protein kinase A (PKA). PKA then phosphorylates CREB, which binds to the cyclic AMP response element (CRE) on DNA, initiating gene transcription.

    • PLC/PKC signaling: A signal activates phospholipase C, which cleaves a membrane phospholipid (PI(4,5)P2) into diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (IP3). DAG activates protein kinase C (PKC). IP3 releases calcium ions from the endoplasmic reticulum. Calcium and calmodulin regulate downstream kinase activity.

    • Calcium/Calmodulin controls downstream kinase activity: Calcium ions bind to calmodulin, causing a conformational change in calmodulin. This activated calmodulin complex then interacts with and regulates target proteins, including kinases, affecting cellular processes.

    • Calcium transients trigger many cellular processes: Calcium release is triggered by various signals, not just GPCRs. These calcium signals regulate diverse processes including skeletal muscle contraction, neurotransmitter release, fertilization, and more.

    • PLC initiates calcium waves in egg activation: Phospholipase C (PLC) triggers calcium waves in egg activation, playing a crucial role in the process.

    • Calcium waves propagate through feedback: IP3 receptors require both IP3 and calcium to function efficiently, leading to a cascade of calcium release and propagation throughout the cell and potentially between cells.

    • How do signaling waves propagate across many cells?: There are examples of wound repair and cellular processes where signaling waves travel across multiple cells.

    • Smell and Vision Depend on GPCRs That Regulate Ion Channels: Olfactory neurons and photoreceptors rely on GPCRs to regulate ion channels, enabling sensory perception.

    • Signals are amplified by cascades: Photoreceptor signaling amplifies light signals by activating multiple proteins in a cascade. A single photon of light can trigger a large change in the membrane potential of the cell, transmitting a signal to the brain.

    • There is cross-talk between many signaling pathways and types of receptors: Different signaling pathways intersect and influence each other.

    • JAK-STAT signaling: Cytokine binding activates JAKs, which phosphorylate STAT proteins. These phosphorylated STATs then dimerize, translocate to the nucleus, and regulate gene transcription.

    • Lab and closing remarks: The next section will cover plant cell culture, and the final exam will include the material from this section along with previous sections.

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    Description

    Test your knowledge on key cell signaling pathways such as cyclic AMP (cAMP) activation and phospholipase C (PLC)/protein kinase C (PKC) signaling. This quiz covers the details of how signaling molecules activate receptors and the subsequent cellular responses. Ideal for students studying cell biology or biochemistry.

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