Exam 2 - Cell Biology / Cell Biochemistry Exam 2 Oct 17,...

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Cell Biology / Cell Biochemistry Exam 2 Oct 17, 2006 Read each question carefully and select the single best answer. 1. The resting membrane potential of neurons is primarily determined by which of the following? a. the sodium concentration gradient b. the asymmetric distribution of phospholipids across the plasma membrane c. the concentration gradient of negatively charged metal ions d. the selective permeability of plasma membrane to calcium ions e. the selective permeability of plasma membrane to potassium ions 2. Voltage-gated sodium channels are composed of a. a single polypeptide with four homologous domains, each containing six transmembrane alpha helices b. a single polypeptide with six homologous domains, each containing four transmembrane alpha helices c. four polypeptides, each containing four transmembrane alpha helices d. four polypeptides each containing six transmembrane alpha helices 3. Which domain of the voltage gated potassium channel is forms the selectivity filter ? a. the P-segment b. the globular N-terminal domain c. the S4 transmembrane alpha helix d. the 3rd intracellular loop e. the C-terminal region
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4. Which domain of the voltage gated potassium channel is forms the voltage sensor ? a. the P-segment b. the globular N-terminal domain c. the S4 transmembrane alpha helix d. the 3rd intracellular loop e. the C-terminal region 5. During the action potential, which event results in re-polarization of the axonal membrane? a. opening of voltage gated sodium channels b. inactivation of voltage gated sodium channels c. opening of voltage gated potassium channels d. closing of voltage gated potassium channels e. opening of voltage gated calcium channels 6. Myelinated axons conduct action potentials much faster than unmyelinated axons because . ... a. myelin is an excellent insulator b. voltage gated ion channels are concentrated at the nodes c. action potential re-generation occurs only at the nodes d. all of the above e. none of the above 7. Why do action potentials propagate along the axon? a. after depolarization, voltage-gated sodium channels inactivate b. after depolarization, voltage-gated potassium channels open c. after depolarization, voltage-gated potassium channels inactivate
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d. electricity always flows along a wire e. it's just one of those electromagnetic things 8. The patch clamp technique is important because . .. a. it keeps neurophysiologists employed b. it is the only way to study action potentials in living cells c. it enables the study of ion channel properties d. it works on cultured cells e. it doesn't require a squid 9. Many inhibitory neurotransmitters hyperpolarize the postsynaptic membrane by opening . ... a. sodium channels
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Exam 2 - Cell Biology / Cell Biochemistry Exam 2 Oct 17,...

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