BSCI 353 Exam 2 Questions and Answers Already Passed Latest Update

BSCI 353 Exam 2 Questions and Answers Already Passed Latest Update What are the two types of synapses? - Answers Electrical synapses (gap junctions, fast, bidirectional) and chemical synapses (neurotransmitter-based, unidirectional, synaptic delay). What is the key structural feature of an electrical synapse? - Answers Gap junctions made of connexons, allowing direct ion flow between neurons. What is the main advantage of electrical synapses? - Answers Speed; they have almost no synaptic delay. What causes the delay in chemical synaptic transmission? - Answers The time required for neurotransmitter release, diffusion, and receptor activation (~1 ms). What triggers neurotransmitter release at a chemical synapse? - Answers Ca2+ influx through voltage-gated calcium channels in the presynaptic terminal. What are SNARE proteins, and why are they important? - Answers Synaptobrevin, SNAP-25, and syntaxin help dock and fuse synaptic vesicles for neurotransmitter release. How does botulinum toxin affect synaptic transmission? - Answers It cleaves SNARE proteins, preventing vesicle fusion and blocking neurotransmitter release. What are the two types of summation in neurons? - Answers Temporal summation: Multiple signals from the same synapse over time. Spatial summation: Inputs from different synapses combining on a neuron. What is the difference between excitatory and inhibitory synaptic inputs? - Answers Excitatory (EPSP): Depolarization (e.g., Na+ influx via glutamate receptors) Inhibitory (IPSP): Hyperpolarization (e.g., Cl- influx via GABA receptors) What role does synaptic vesicle recycling play? - Answers Prevents vesicle depletion by reforming vesicles after neurotransmitter release. How does α-latrotoxin (black widow toxin) affect synaptic transmission? - Answers It triggers massive neurotransmitter release by forming Ca2+-permeable pores in presynaptic neurons. What are the two main types of neurotransmitters? - Answers Small-molecule neurotransmitters (e.g., glutamate, GABA, acetylcholine) and neuropeptides (e.g., substance P, endorphins). Where are peptide neurotransmitters synthesized? - Answers Rough ER → processed in the Golgi apparatus → transported to synaptic terminals in large, dense-core vesicles. What are the two major types of neurotransmitter receptors? - Answers Ionotropic (ligand-gated ion channels) and Metabotropic (G-protein-coupled receptors, GPRCs). What is the main difference between ionotropic and metabotropic receptors? - Answers Ionotropic receptors act fast by directly gating ion channels, while metabotropic receptors act slowly via second messenger signaling. What are examples of ionotropic receptors? - Answers AMPA, NMDA (glutamate), GABA_A (GABA), nicotinic ACh receptor (acetylcholine). What are examples of metabotropic receptors? - Answers mGluRs (glutamate), GABA_B (GABA), muscarinic ACh receptors (acetylcholine), dopamine receptors. What are the major excitatory and inhibitory neurotransmitters in the CNS? - Answers Excitatory: Glutamate (depolarizes neurons via Na+ influx). Inhibitory: GABA & glycine (hyperpolarize neurons via Cl- influx). What enzyme synthesizes acetylcholine (ACh)? - Answers Choline acetyltransferase (ChAT). Which neurotransmitter is affected by sarin gas? - Answers Acetylcholine (sarin inhibits acetylcholinesterase, causing excessive ACh accumulation). What neurotransmitter do motor neurons release at the neuromuscular junction? - Answers Acetylcholine (ACh). What is the role of dopamine in the brain? - Answers Involved in reward, motivation, movement control (degeneration leads to Parkinson's disease). How do SSRIs (Selective Serotonin Reuptake Inhibitors) work? - Answers They block serotonin reuptake, increasing serotonin levels in the synaptic cleft. What type of receptor is a muscarinic acetylcholine receptor (mAChR)? - Answers Metabotropic GPCR (NOT ionotropic) Which statements about muscarinic ACh receptors are false? They do NOT control ligand-gated ion channels. They do NOT mediate rapid responses to ACh. They do NOT activate voltage-gated Na+ channels. They do NOT mediate neuromuscular junction effects (those use nicotinic ACh receptors). - Answers None of the statements are false — they are all TRUE. What are the three major types of cell signaling? - Answers Synaptic (fast, local), paracrine (local diffusion), endocrine (long-distance, via bloodstream). What are the three main components of intracellular signaling? - Answers Signal (ligand), receptor, intracellular transduction cascade. What are the three major types of neurotransmitter receptors? - Answers Ionotropic (ligand-gated ion channels), metabotropic (GPCRs), enzyme-linked receptors. What are G-protein-coupled receptors (GPCRs)? - Answers Metabotropic receptors that activate intracellular signaling cascades via G-proteins. What are the three types of G-protein subunits? - Answers Gα, Gβ, Gγ. What are the three types of Gα proteins and their functions? - Answers Gαs: Stimulates adenylyl cyclase → increases cAMP → activates PKA Gαi: Inhibits adenylyl cyclase → decreases cAMP. Gαq: Activates phospholipase C (PLC) → produces IP₃ & DAG → increases Ca²⁺ release & PKC activation. What is the effect of the cholera toxin on G-protein signaling? - Answers Cholera toxin locks Gαs in an active state, leading to increased cAMP and increased PKA activation.