Exam (elaborations) Neuroscience - Molecular Signaling within Neurons

In what way does the function of monomeric G-proteins differ from that of heterotrimeric G-proteins? a. Monomeric G-proteins are active in the GTP-bound state, heterotrimeric G-proteins are not. b. Heterotrimeric G-protein activation is controlled by guanine nucleotide exchange factors, monomeric G-protein activation is not. c. Heterotrimeric G-proteins relay signals from cell surface receptors to intracellular targets, monomeric G-proteins do not. d. Monomeric G-protein activity is terminated by hydrolysis of GTP, heterotrimeric Gprotein activity is not. e. Heterotrimeric G-protein activity is regulated by GAP proteins, monomeric G-protein activity is not. Answer: b Textbook Reference: G-Proteins and Their Molecular Targets 10. Which molecule is an effector directly downstream of an activated G-protein? a. Phospholipase C b. IP3 c. cAMP d. Protein kinase C e. Protein kinase A Answer: a Textbook Reference: G-Proteins and Their Molecular Targets 11. Which role does calmodulin play in the intracellular cascade triggered by Ca2+? a. It modulates the strength of Ca2+ binding to its downstream targets. b. It serves as a Ca2+ buffer. c. It enhances downstream effects of Ca2+ d. It binds to its downstream targets when activated by Ca2+ e. It serves as a Ca2+ sensor when neurotransmitter is released. Answer: d Textbook Reference: Second Messengers 12. In which direction do Ca2+ ions flow through ryanodine receptors? a. From the cytoplasm into the endoplasmic reticulum b. From the endoplasmic reticulum into the cytoplasm c. From the extracellular space into the cytoplasm d. From the cytoplasm into the extracellular space e. From the cytoplasm into synaptic vesicles Answer: b Textbook Reference: Second Messengers 13. Which second messenger originates from both extracellular and intracellular compartments? a. Ca2+ b. Cyclic AMP c. Cyclic GMP d. IP3 e. Diacylglycerol Answer: a Textbook Reference: Second Messengers 14. Which second messenger plays an important role in sensory transduction processes? a. Ca2+ b. Cyclic nucleotide c. Nucleotide d. IP3 e. Diacylglycerol Answer: b Textbook Reference: Second Messengers 15. Which of the following provides an example of a second messenger producing another second messenger? a. IP3 binds to its receptor, enabling the release of Ca2+ from the cytosol. b. Diacylglycerol fuses with PIP2, producing IP3. c. Phospholipase C acts on PIP2, splitting it into IP3 and diacylglycerol. d. Ca2+ binds to calmodulin, promoting its binding to downstream protein kinases. e. G-proteins activate adenylyl cyclase in the plasma membrane, causing it to produce cyclic nucleotides. Answer: a Textbook Reference: Second Messengers