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#membrane potential

5 public questions tagged with this topic.

Membrane Transportation

Which segment of a voltage-gated ion channel detects changes in membrane potential?

Ion channel gating requires conversion of electrical signal into conformational change, accomplished by specialized sensor modules. Voltage-gated channels share a conserved architecture of four domains each comprising six membrane helices. S1, S2 and S3 are largely hydrophobic with interspersed acidic residues forming a charge transfer center and hydrophilic vestibules enabling helix motion. S4 stands out because it contains four to seven positively charged arginine or lysine residues spaced every third position in motif Arg-X-X-Arg, creating a linear array of gating charges along one face of

Ref: Lodish et al., Molecular Cell Biology, 9th ed., Chapter: Voltage-Sensing Domain S4 Movement and Gating Currents.

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Membrane Transportation

Which of the following is a voltage-gated sodium channel subunit responsible for sensing membrane potential?

Voltage-gated sodium channels that drive rapid upstroke of action potentials are built from one polypeptide folded into four homologous repeats, each repeat having six transmembrane helices S1 to S6. S1 through S4 cluster peripherally as the voltage-sensing domain, while S5, S6 and the intervening loop dip back into the membrane as P-loop to create the ion conducting pore. The hallmark of voltage sensing resides in S4, which exhibits a repeating pattern Arg-X-X where positively charged arginine or lysine appears every third residue, flanked by hydrophobic side chains. These gating charges sit

Ref: Alberts et al., Molecular Biology of the Cell, 7th ed., Chapter 11: Voltage-Gated Ion Channels and Electrical Properties of Membranes.

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Membrane Transportation

Which of the following is a voltage-gated ion channel?

Gating mechanisms classify ion channels by physiological stimulus that controls transition from closed to open conformation. Voltage-gated channels possess specialized voltage-sensing domains where transmembrane segment S4 contains repeating positively charged arginine or lysine residues every third position, acting as sliding helix that moves outward upon membrane depolarization, pulling on S4-S5 linker and opening activation gate at intracellular bundle crossing. Neuronal voltage-gated sodium channels, Nav1.1 to Nav1.9 encoded by SCN genes, contain four homologous domains each with six helic

Ref: Hille, Ion Channels of Excitable Membranes, 3rd ed., Chapter 5: Voltage-Gated Sodium Channels in Neurons.

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Action potential

Overshoot phase of action potential occurs because membrane potential moves toward equilibrium potential of:

Answer: B) Na+. For Action potential, once you lock onto the key mechanism or definition, Na+ is the clear fit. If you restate the concept in your own words, cause and effect line up with Na+ — that is the mechanism or reason the stem is pointing to. So Na+ is the clean, accurate selection. If a similar stem appears later, start from the same core fact and you will land on the same kind of answer. In class notes, highlight this same phrase next to the related diagram so the wording and the picture reinforce each other. When you practise, cover the choices first, write Na+ from memory, then rev

Ref: Animal physiology is Unit 7 of the CSIR NET Life Science Syllabus, covering core body systems. It accounts for roughly 10% of the total marks in Sections B and C.

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