D. steroid receptor Consider a cell with an intracellular concentration of chlor
ID: 206369 • Letter: D
Question
D. steroid receptor Consider a cell with an intracellular concentration of chloride ions ICT] of 10 mM. The extracellalar ICTI is 0.01 mM. The transmembrane membrane potential is-90 mV, negative inside. Which is true? A. The chemical force due to the concentration gradient would favor flow of Cl into the cell. B. The electrical force due to the transmembrane gradient would favor flow of CT into the cel. C. Both the chemical force and the electrical force would favor flow of Ca out of the cell. D. Cl is at equilibrium and no net flow of CI would occur. A eell has an intracellular glucose concentration (Iglucose]a) of 5 mM while the extracellular glucose concentration (Iglucoseleat) is 50 mM. The transmembrane membrane potential is-90 mV, negative inside. Which is true with respeet to the free energy for flow of glucose into the cell? A. It is positive and therefore thermodynamically unfavorable. B. It is zero because glucose is not charged. C. It is negative and thermodynamically favorable. D. The free energy is dependent on the transmembrane potential. Complete the sentence. Receptor tyrosine kinases A. form cAMP when activated by extracellular ligands B. mediate signaling by the hormone insulin. C. form transmembrane ion channels when activated. D. are peripheral membrane proteins. , Fill in the blanks. The Ga subunit of heterotrimeric G proteins is an important activator of the enzyme- which produces the second messenger molecule A. adenylyl cyclase (AC) and cyclic AMP (CAMP). B. phosphodiesterase (PDE) and adenosine monophosphate (AMP). C. guanylyl cyclase and guanosine diphosphate (GDP) D. phospholipase C and cyelic AMP (CAMP).Explanation / Answer
1) The difference in concentration of ions inside and outside the cell, results in a voltage across the semipermeable membrane. The difference between this voltage, outside and inside the cell is the membrane potential.
If the concentration gradient for an ion is same, or ion concentration is similar in the intracellular fluid and the extracellular fluid, the transmembrane potential alone governs the movement of the ions. In this case, for a negative transmembrane potential of -90mV, the Chloride ions (or anions) would move from intracellular fluid to extracellular fluid and would be drive by the membrane potential. This is the electrical driving force.
Also, there is a difference in concentration gradient. The intracellular [Cl-] is 10mM, while extracellular is [Cl-] is 0.01mM. At equilibrium membrane potential, the chemical driving force would move Chloride ions from intracellular fluid to extracellular fluid (Higher to lower concentration).
Equilibrium potential may be described and calculated using Nernst equation, described as:
E=RT/zF ln([Xi]/[Xo])
E is equilibrium potential
R is the universal gas constant and is equal to 8.314 J.K-1.mol-1 (Joules per Kelvin per mole).
T is the temperature in Kelvin (K = °C + 273.15).
z is the valence of the ion.
F is the Faraday's constant and is equal to 96485 C.mol-1 (Coulombs per mole).
[X]o is the concentration of the ion X, in the extracellular fluid.
[X]i is the concentration of the ion X, in the intracellular fluid.
Considering temperature of 37°C = 298.15 K
For Chloride, z =-1
In this case, [X]o = 0.01 mM, [X]I = 10mM
Thus, substituting the values,
Correct option is C
2) Free Energy may be calculated as: G = RT ln([Xi]/[Xo])
R is the universal gas constant and is equal to 8.314 J.K-1.mol-1 (Joules per Kelvin per mole).
T is the temperature in Kelvin (K = °C + 273.15)
[X]o is the concentration of the ion X, in the extracellular fluid.
[X]i is the concentration of the ion X, in the intracellular fluid.
Considering temperature of 37°C = 298.15 K
In this case, [X]o = 50 mM, [X]I = 5mM
Thus correct option is A.
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