Intracellular Signalling Molecules Quiz
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Questions and Answers

What is the composition of a G protein?

  • α, β, δ
  • α, β, γ (correct)
  • β, γ, δ
  • α, γ, δ

In the unstimulated state, the α subunit of a G protein is bound to:

  • ATP
  • ADP
  • GTP
  • GDP (correct)

What happens to the GTP-bound α subunit of a G protein when activated by a ligand-bound receptor?

  • It dissociates from the βγ dimer (correct)
  • It activates phospholipase C
  • It binds back to the βγ dimer
  • It associates with the receptor

Which enzyme is activated by cAMP produced in response to GPCR activation?

<p>Protein Kinase A (PKA) (C)</p> Signup and view all the answers

What is the cellular response to activation of the β2 Adrenergic Receptor?

<p>Modulation of gene transcription (A)</p> Signup and view all the answers

What characterizes Enzyme-Linked Receptors?

<p>Integral membrane proteins with a single transmembrane domain (A)</p> Signup and view all the answers

Which of the following receptors are directly coupled to ion channels, allowing for rapid electrical signal transduction?

<p>Ion channel-coupled receptors (D)</p> Signup and view all the answers

Which type of receptor initiates signaling cascades involving second messengers like cAMP, cGMP, and PIP3?

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

Which of the following ligands typically binds to G protein-coupled receptors?

<p>Adrenaline (B)</p> Signup and view all the answers

Which type of receptor is directly involved in the regulation of gene expression?

<p>Intracellular steroid receptors (B)</p> Signup and view all the answers

Which of the following signaling molecules can directly cross the plasma membrane due to their hydrophobic nature?

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

Which type of receptor is typically associated with tyrosine kinase activity and involved in the regulation of cell growth and differentiation?

<p>Enzyme-linked receptors (catalytic receptors) (C)</p> Signup and view all the answers

Which of the following statements about G-protein-coupled receptors (GPCRs) is correct?

<p>GPCRs share a common structure with seven transmembrane domains and interact with trimeric G proteins. (C)</p> Signup and view all the answers

What is the primary role of the trimeric G protein in the GPCR signaling pathway?

<p>To transfer the signal from the activated GPCR to downstream effector proteins. (D)</p> Signup and view all the answers

Which of the following is NOT an example of a ligand that can activate GPCRs?

<p>Protons (H+ ions) (A)</p> Signup and view all the answers

In the context of ion-channel-coupled receptors, what is the primary function of acetylcholine (Ach) at the neuromuscular junction?

<p>To open ligand-gated Na$^+$ channels in the muscle cell membrane, leading to depolarization. (A)</p> Signup and view all the answers

What is the role of Ca$^{2+}$ ions in the process of muscle contraction triggered by ion-channel-coupled receptors?

<p>Ca$^{2+}$ ions are released from the sarcoplasmic reticulum into the cytosol, leading to contraction of myofibrils. (B)</p> Signup and view all the answers

Which of the following statements about the signaling mechanisms of GPCRs and ion-channel-coupled receptors is correct?

<p>GPCRs activate G proteins, while ion-channel-coupled receptors directly open ion channels. (A)</p> Signup and view all the answers

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