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5.0
Bio 3P03 Exam Recent Questions with Detailed
Verified Answers and Correct Answers Already
Graded A+
Q: When will diffusion be the fastest between compartments?
Ans: when there is a large difference in # of molecules between them (flux is
proportional to change in conc)
Q: 3 important properties of ion channels
Ans: 1) conduct ions across membrane
2) select specific ions
3) open/close in response to mechanical, electrical, or chemical signals
Q: Even though Na+ is smaller than K+, why doesn't Na+ fit through
highly-selective K+ channel (KcsA)?
Ans: Na+ has stronger electric field, so bigger hydration cloud, thus it
behaves bigger than K+ and cannot pass through the K+ channel
pores
Q: Which of the following types of ion channels is a monomeric
protein? Ligand-gated, gap-junction, voltage-gated.
Ans: Voltage-gated (all motifs are connected)
Q: In a voltage-gated channel, how many motifs/transmembrane
domains?
Ans: 4
Sunday, 02 March 2025
,Q: Where is the voltage sensor in a voltage-gated channel?
Ans: alpha helix 4 (S4) - contains positive amino acids
Q: Where is the selectivity filter in a voltage-gated channel?
Ans: the P loops between alpha helices 5 & 6 in each domain
Q: Inside-out patch clamp
Ans: electrode is quickly withdrawn from cell in cell-attached configuration
(exposes inside of membrane to external solution)
- good for studying cytoplasmic factors affecting inside surface of channel
Q: Outside-out patch clamp
Ans: electrode is slowly withdrawn from whole-cell mode (exposes outside
surface of membrane to external solution)
- good for studying ligand-gated channels (apply ligand to bathing solution)
Q: Hyperkalemic periodic paralysis
Ans: mutation alters function of voltage-gated Na+ channels so that they're
unable to close inactivation gates.
Triggered by high serum K+ levels & results in periodic muscle paralysis
Q: What does the ion equilibrium potential (Eion) respresent?
Examstudy - Stuvia US
, Ans: when electrical gradient = chemical gradient (ie. no net movement)
Q: Formula for Eion
Ans: Eion = 58mv/z(log [outside]/[inside])
Q: What is membrane potential (Vm)?
Ans: the difference in voltage across the membrane
Q: How to calculate Vm
Ans: GHK Equation:
Vm = P[K]o + P[Na]o + P[Cl]i/(P[K]i + P[Na]i + P[Cl]o
Q: What is the permeabilities for K, Na & Cl-?
Ans: Pk = 1
Pna = 0.04
Pcl = 0.45
Q: Depolarization is a increase or reduction of charge separation?
Ans: reduction or reversal or charge separation = depolarization
Q: What ion is most permeable at rest?
Ans: K+
Q: How do impermeable ions affect the cell?
Examstudy - Stuvia US
In today's fast-paced educational landscape, students need reliable resources to excel in their studies.
5.0
Bio 3P03 Exam Recent Questions with Detailed
Verified Answers and Correct Answers Already
Graded A+
Q: When will diffusion be the fastest between compartments?
Ans: when there is a large difference in # of molecules between them (flux is
proportional to change in conc)
Q: 3 important properties of ion channels
Ans: 1) conduct ions across membrane
2) select specific ions
3) open/close in response to mechanical, electrical, or chemical signals
Q: Even though Na+ is smaller than K+, why doesn't Na+ fit through
highly-selective K+ channel (KcsA)?
Ans: Na+ has stronger electric field, so bigger hydration cloud, thus it
behaves bigger than K+ and cannot pass through the K+ channel
pores
Q: Which of the following types of ion channels is a monomeric
protein? Ligand-gated, gap-junction, voltage-gated.
Ans: Voltage-gated (all motifs are connected)
Q: In a voltage-gated channel, how many motifs/transmembrane
domains?
Ans: 4
Sunday, 02 March 2025
,Q: Where is the voltage sensor in a voltage-gated channel?
Ans: alpha helix 4 (S4) - contains positive amino acids
Q: Where is the selectivity filter in a voltage-gated channel?
Ans: the P loops between alpha helices 5 & 6 in each domain
Q: Inside-out patch clamp
Ans: electrode is quickly withdrawn from cell in cell-attached configuration
(exposes inside of membrane to external solution)
- good for studying cytoplasmic factors affecting inside surface of channel
Q: Outside-out patch clamp
Ans: electrode is slowly withdrawn from whole-cell mode (exposes outside
surface of membrane to external solution)
- good for studying ligand-gated channels (apply ligand to bathing solution)
Q: Hyperkalemic periodic paralysis
Ans: mutation alters function of voltage-gated Na+ channels so that they're
unable to close inactivation gates.
Triggered by high serum K+ levels & results in periodic muscle paralysis
Q: What does the ion equilibrium potential (Eion) respresent?
Examstudy - Stuvia US
, Ans: when electrical gradient = chemical gradient (ie. no net movement)
Q: Formula for Eion
Ans: Eion = 58mv/z(log [outside]/[inside])
Q: What is membrane potential (Vm)?
Ans: the difference in voltage across the membrane
Q: How to calculate Vm
Ans: GHK Equation:
Vm = P[K]o + P[Na]o + P[Cl]i/(P[K]i + P[Na]i + P[Cl]o
Q: What is the permeabilities for K, Na & Cl-?
Ans: Pk = 1
Pna = 0.04
Pcl = 0.45
Q: Depolarization is a increase or reduction of charge separation?
Ans: reduction or reversal or charge separation = depolarization
Q: What ion is most permeable at rest?
Ans: K+
Q: How do impermeable ions affect the cell?
Examstudy - Stuvia US
