Calculate the free energy required to move 1 mol of K* ions from inside the cell (where concentration of K+= 0.063 M) to the outside the cell (where concentration K+= 0.17 M). The membrane potential is -0.05 V and the temperature is 303.06 K. K+ (inside cell) → K* (outside cell)

In the situations described below, what is the free energy change if 1 mole of Na+ is transported across a membrane from a region where the concentration is 48 μM to a region where it is 110 mM? (Assume T=37∘C.) In the absence of a membrane potential.

Suppose that certain cells found in an organism are permeable to both CI" and Kt ions but no other ions at rest. The intra- and extracellular concentrations of both ions for these cells are shown below. The resting membrane potential is -75 mV. Assume that passage of both ions across the membrane occurs through ion channels that are selective for each ion. [Intracellular] [Extracellular] CI 4 mM 110 mM K+ 25 mM 100 mM Based on this information, what reasonable conclusion can you draw about the relative permeabilities of K* and CI" ions in these neurons at rest based on what we discussed? а. The membrane is more permeable to chloride ions than to potassium ions at rest. b. The membrane is more permeable to potassium ions than to chloride ions at rest. С. At rest, the membrane potential of these neurons lies closer to the potassium equilibrium potential (EK) than it does to the chloride equilibrium potential (ECI). d. Both a and c е. Both b and c

3L9

Below find the structures for ibogaine and cocaine. Ibogaine and cocaine inhibit the dopamine active transporter (DAT).  This transporter is a secondary active transporter, and depends on the primary active transporter Na+/K+ ATPase.  Ibogaine had a Kι = 2 μM, and cocaine a Kι = 0.64 μM respectively. (a) Define secondary active transport. (b) Is ibogaine an effective treatment for cocaine based on DAT binding?

Not too sure if my answer is correct.

A one-to-one protein (P)-ligand (L) complexation (P + L PL) has a dissociation equilibrium constant (Kd) value of 100 nM at 25°C, and the Kd remains the same at 37°C. 1) What is AS of binding at 25°C? Assume ACp of the binding is 0 over the temperature range. AS = 1.34E2 kJ/(mol*K) (note the unit!!) (sig. fig =3) 2) What is the concentration of the PL complex formed at equilibrium when you mix 0.20 uM (microM) of Protein and 1.0 uM of Ligand together at 37°C? PL at equilibrium = 8.1E-1 uM (note the unit!!) (sig. fig =2)

bo Consider a uniport system where a carrier protein transports an uncharged substance A across a cell membrane. Suppose that at a certain ratio of [A] inside to [A] outside, the AG for the transport of substance A from outside the cell to the inside, Macmillan Leaming A outside → Ainside, is 10.7 kJ/mol at 25°C. What is the ratio of the concentration of substance A inside the cell to the concentration outside? [A]inside [A]outside Choose the true statement about the transport of A under the conditions described. Because AG is positive, the ratio [A] inside/[A]outside must be less than one. Increasing [A]outside will cause AG for movement of Aoutside to Ainside to become a larger positive number. Movement of Ainside to Aoutside will be spontaneous. Decreasing the concentration of the uniport protein in the membrane will cause AG to become a smaller positive number.

The uptake of l-ascorbate (vitamin C) and its oxidized form, dehydro-l-ascorbic acid (DHAA), was evaluated in brush border membrane vesicles isolated from adult human small intestine. Ascorbate uptake was Na+-dependent and potential-sensitive (Km, 200 umol/L), whereas DHAA transport occurred through Na+-independent facilitated diffusion (Km, 800 µmol/L). If the Vmax of vitamin C import through channels is 401µmol/min/cm², what import rate would you expect if the lumen contained 133 µmol/L of the version of vitamin C that moves through them?

The antibiotic valinomycin is an ionophore that forms a specific complex with potassium ion. Because the complex is lipophilic and can diffuse into the membrane, valinomycin brings about the transport of K+ through the inner membrane. Valinomycin acts by decreasing the ∆ψ (membrane potential) component of the pmf, without a direct effect on the pH gradient. Another antibiotic, nigericin, acts as a K+ >H+ antiporter; itcarries H+ in one direction, coupled with the reverse transport of K+. Thus,nigericin dissipates the pH component of the pmf, with little effect on ∆c.Which antibiotic, nigericin or valinomycin, do you predict would have thegreater effect on oxidative phosphorylation when administered to respiring mitochondria? Assume the antibiotics are added to a suspension of mitochondria in equimolar amounts. Briefly explain your reasoning.