Mini 1 Part 2 Cell Signaling

15 Questions | Total Attempts: 740

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Cell Nucleus Quizzes & Trivia

Mini practice quiz


Questions and Answers
  • 1. 
    The second messenger cAMP induces its effects by binding to the regulatory subunits of protein kinase A. What is the immediate target of the second messenger IP3?
    • A. 

      A calcium channel in the ER membrane

    • B. 

      Phospholipase C

    • C. 

      Protein kinase C

    • D. 

      A nuclear DNA-binding protein

    • E. 

      Calmodulin

  • 2. 
    Glucagon can induce gene transcription in the liver.  How?
    • A. 

      It is translocated to the nucleus where it binds to response elements in the regulatory sequences of the genes.

    • B. 

      It triggers cAMP formation, and cAMP activates genes by binding to the catabolite activator protein

    • C. 

      It releases calcium from the ER, which activates protein kinase C in the nucleus

    • D. 

      It causes phosphorylation of nuclear transcription factors by protein kinase A

    • E. 

      It induces the formation of the second messenger IP3, which activates transcription by binding to nuclear transcription factors

  • 3. 
    What is the difference between nicotinic and muscarinic acetylcholine receptors?
    • A. 

      Nicotinic: has guanylate cyclase activity; muscarinic: ion channel

    • B. 

      Nicotinic: ion channel; muscarinic: coupled to G-proteins

    • C. 

      Nicotinic: coupled to G-proteins; muscarinic: has adenylate cyclase activity

    • D. 

      Nicotinic: coupled to G-proteins; muscarinic: ion channel

    • E. 

      Nicotinic: ion channel; muscarinic: has tyrosine-specific protein kinase activity

  • 4. 
    Inositol 1,4,5-trisphosphate (IP3) is a second messenger of many hormones. To form this second messenger, you need the enzyme:
    • A. 

      Phosphodiesterase

    • B. 

      Protein kinase C

    • C. 

      Protein kinase B

    • D. 

      Phospholipase C

    • E. 

      Ras

  • 5. 
    CAMP stimulates hormone production and cell proliferation in many endocrine tissues including the thyroid gland. Therefore a type of somatic mutation that is most likely to lead to the formation of a hormone-overproducing benign tumor in the thyroid gland (a "toxic nodule") is one that causes:
    • A. 

      Inability of the Gs protein to hydrolyze its bound GTP

    • B. 

      Inability of the Gi protein to hydrolyze its bound GTP

    • C. 

      Inability of the protein kinase A regulatory subunits to respond to cAMP

    • D. 

      Absence of the CREB (cyclic AMP response element binding) protein

    • E. 

      Degeneration of the TSH-producing thyrotrophs in the anterior pituitary gland

  • 6. 
    There is much overlap of the intracellular signaling cascades of growth factors such as EGF (epidermal growth factor) and PDGF (platelet-derived growth factor) with those triggered by:
    • A. 

      Neurotransmitters

    • B. 

      Hormones acting through cGMP

    • C. 

      Steroid hormones

    • D. 

      Insulin

    • E. 

      Hormones that are coupled to heterotrimeric G proteins

  • 7. 
    Many cytoplasmic enzymes become activated in response to an elevated calcium concentration.  In most cases these effects are mediated by the protein:
    • A. 

      Calmodulin

    • B. 

      Phospholipase A2

    • C. 

      Troponin

    • D. 

      Calsequestrin

    • E. 

      Calcineurin

  • 8. 
    One important feature of the insulin receptor is:
    • A. 

      It phosphorylates proteins on tyrosine side chains

    • B. 

      It is coupled to the Gi protein

    • C. 

      It is coupled to the Gq protein

    • D. 

      It has guanylate cyclase activity

    • E. 

      It mediates many of its effects through the production of nitric oxide (NO)

  • 9. 
    A linkage study has found that there is a gene for test taking skill in a particular region on the long arm of chromosome 4. A search of the human genome sequence shows that this chromosomal region contains a gene of unknown function. This gene encodes a protein that has not only a signal sequence, but also seven hydrophobic sequences, each about 20 amino acid residues long. The gene product is most likely:
    • A. 

      A voltage-gated ion channel

    • B. 

      A ligand-gated ion channel

    • C. 

      A cytoplasmic protein kinase

    • D. 

      A hormone receptor that is linked to G-proteins

    • E. 

      A hormone receptor with a tyrosine-specific protein kinase activity

  • 10. 
    Some hormones act by triggering the release of calcium from the endoplasmic reticulum. These hormones can regulate gene expression, usually by:
    • A. 

      The binding of calcium to transcription factors, which in turn bind to promoters and enhancers of genes

    • B. 

      The activation of calmodulin-regulated protein kinases that phosphorylate nuclear transcription factors

    • C. 

      The direct binding of calcium to the DNA double helix

    • D. 

      The methylation of DNA in the promoters and enhancers of genes by a calcium-dependent enzyme

    • E. 

      The binding of calcium to mRNA, which stabilizes the RNA against the action of RNA-degrading enzymes

  • 11. 
    You work as research director for a pharmaceutical company. One of your tasks is the development of new anti-hypertensive (blood pressure lowering) drugs. Of the following, the most promising drug would be one that:
    • A. 

      Inhibits the endothelial nitric oxide synthase

    • B. 

      Opens voltage-gated calcium channels in the plasma membrane of vascular smooth muscle cells

    • C. 

      Blocks voltage-gated calcium channels in the plasma membrane of endothelial cells but not vascular smooth muscle cells

    • D. 

      . Inhibits the Gs protein in vascular smooth muscle cells

    • E. 

      Prevents the degradation of cAMP in vascular smooth muscle cells but not other cells in the body

  • 12. 
    The actions of insulin are initiated by:
    • A. 

      Phosphorylation of the insulin receptor on tyrosine side chains

    • B. 

      Stimulation of cAMP synthesis through a G-protein

    • C. 

      Inhibition of cAMP synthesis through a G-protein

    • D. 

      Formation of IP3 and DAG

    • E. 

      Activation of a guanylate cyclase

  • 13. 
    A patient is found to have a small benign tumor in the thyroid gland that overproduces thyroid hormones. The somatic mutation that is most likely to cause this tumor is one that
    • A. 

      Causes the pituitary gland to overproduce TSH

    • B. 

      Prevents hydrolysis of bound GTP by the Gs protein

    • C. 

      Prevents binding of TSH to the TSH receptor

    • D. 

      Prevents the activation of phospholipase C by a G-protein

    • E. 

      Prevents the activation of protein kinase A

  • 14. 
    Growth factors and insulin can regulate gene expression. Which mechanism is most likely to contribute to this effect?
    • A. 

      Dephosphorylation of transcription factors by the protein phosphatase calmodulin

    • B. 

      Binding of the Ras protein to the promoters and enhancers of genes

    • C. 

      Phosphorylation of transcription factors by MAP kinases

    • D. 

      Phosphorylation of a catabolite activator protein in the nucleus

    • E. 

      Phosphorylation of the CREB protein on tyrosine side chains

  • 15. 
    Many cytoplasmic enzymes become activated in response to an elevated calcium concentration.  In most cases these effects are mediated by the protein
    • A. 

      Calmodulin

    • B. 

      Phospholipase A2

    • C. 

      troponin

    • D. 

      Calsequestrin

    • E. 

      Calcineurin

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