a. Substance X is transported by passive transport and Substance Y is transported by active transport b. Substance X is transported by active transport and Substance Y is transported by passive transportc. Substance X is transported by active transport and Substance Y is transported by active transportd. Substance X is transported by passive transport and Substance Y is transported by passive transport The transport of two substances across cell membranes was investigated by incubating cells in increasing concentrations of eachsubstance and measuring the amount that crosses the membrane. Only one molecule is being transported against itsconcentration gradient. The results are depicted in the figure below:Which of the following statements are true?Transportrate(Units/m)Y.ConcentrationK7

Membrane transport refers to the movement of solute substances across or through a membranous…

Substance X is transported by passive transport and Substance Y is transported by active transport b. Substance X is transported by active transport and Substance Y is transported by passive transport c. Substance X is transported by active transport and Substance Y is transported by active transport d. Substance X is transported by passive transport and Substance Y is transported by passive transport

Substance X is transported by passive transport and Substance Y is transported by active transport b. Substance X is transported by active transport and Substance Y is transported by passive transport c. Substance X is transported by active transport and Substance Y is transported by active transport d. Substance X is transported by passive transport and Substance Y is transported by passive transport

Human Physiology: From Cells to Systems (MindTap Course List)

9th Edition

ISBN:9781285866932

Author:Lauralee Sherwood

Publisher:Lauralee Sherwood

Chapter3: The Plasma Membrane And Membrane Potential

Section: Chapter Questions

Problem 6RE

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One of the important uses of the Nernst equation is in describing the flow of ions across plasma membranes. Ions move under the influence of two forces: the concentration gradient (given in electrical units by the Nernst equation) and the electrical gradient (given by the membrane voltage). This is summarized by Ohms law: Ix=Gx(VmEx) which describes the movement of ion x across the membrane. I is the current in amperes (A); G is the conductance, a measure of the permeability of x, in Siemens (S), which is I/V;Vm is the membrane voltage; and Ex is the equilibrium potential of ion x. Not only does this equation tell how large the current is, but it also tells what direction the current is flowing. By convention, a negative value of the current represents either a positive ion entering the cell or a negative ion leaving the cell. The opposite is true of a positive value of the current. a. Using the following information, calculate the magnitude of Na [ Na+ ]0=145mM,[ Na+ ]i=15mM,Gna+=1nS,Vm=70mV b. Is Na+ entering or leaving the cell? c. Is Na+ moving with or against the concentration gradient? Is it moving with or against the electrical gradient?
Assume that a membrane permeable to Na+ but not to Cl- separates two solutions. The concentration of sodium chloride on side 1 is higher than on side 2. Which of the following ionic movements would occur? a. Na+ would move until its concentration gradient is dissipated (until the concentration of Na+ on side 2 is the same as the concentration of Na+ on side 1). b. Cl- would move down its concentration gradient from side 1 to side 2. c. A membrane potential, negative on side 1, would develop. d. A membrane potential, positive on side 1, would develop. e. None of the preceding is correct.
List the means of unassisted membrane transport.
The transport of a molecule is investigated using two chambers (left and right) separated by a synthetic membrane containing transport proteins. A solution containing varying concentrations of the molecule is added to the left side while pure water is added to the right. The transport rate of the molecule is determined by measuring the concentration of molecule that accumulates on the right side. The following table summarizes the transport rate of the molecule at various concentrations. Based on this you can conclude: a) the molecule is most likely transported by facilitated diffusion b) the molecule is moving across the membrane by passive transport c) the membrane is freely permeable to the molecule d) the molecule is most likely transported by active transport
Liver cells are in contact with the blood and exchange a variety of substances with the blood plasma (the noncellular part of blood). The concentration of water is equal in the cytoplasm of liver cells and in the blood plasma. Explain this observation in terms of membrane permeability and transport mechanisms. Animal cells typically maintain a higher concentration of Na+ outside the cell and a higher concentration of K+ inside the cell via the Na+-K+ pump. The drug ouabain inhibits the activity of the Na+-K+ pump. A nerve cell is incubated in ouabain. Predict what will happen to the concentrations of Na+ and K+ inside and outside the nerve cell as a result.
A membrane separates Solution A and Solution B. The membrane has a permeability of 2 x 105 cm/s to urea and has a surface area of 5 cm2. The concentration of urea in Solution A is 2 mg/mL. The initial rate of net diffusion of urea is 1 x 104 mg/s. What is the concentration of urea in Solution B?
The type of transport shown in this figure is best described by which of the following pairs of terms: Low High High Low
Name the three classes of membrane transport proteins. Explain which one or ones of these classes is able to move glucose and which can move bicarbonate (HCO3−) against an electrochemical gradient. In the case of bicarbonate, but not glucose, the ΔG of the transport process has two terms. What are these two terms, and why does the second not apply to glucose? Why are cotransporters often referred to as examples of secondary active transport?
Name the three classes of membrane transport proteins. Explain which one or ones of these classes is able to move glucose and which can move bicarbonate (HCO3 −) against an electrochemical gradient. In the case of bicarbonate, but not glucose, the ΔG of the transport process has two terms.What are these two terms, and why does the second not apply to glucose? Why are cotransporters often referred to as examples of secondary active transport?
Uniporters and ion channels support facilitated transport across cellular membranes. Although both are examples of facilitated transport, the rates of ion movement via an ion channel are roughly 104- to 105-fold faster than the rates of molecule movement via a uniporter. What key mechanistic difference results in this large difference in transport rate? What contribution to free energy (ΔG) determines the direction of transport?
B) Rate of transport into the cll A or B 10 20 30 40 Time (min) The graph directly above shows the rate of substance transport over time when the cells that do not contain the compounds A, B, or C, are placed in 1 mM solutions of A, B, and C, respectively. Based upon these data which of the following is/are compatible modes of transport for substance A? (active transport, facilitated diffusion, simple diffusion) For substance B? For substance C?
Uniporters and ion channels support facilitated transport across cellular membranes. Although both are examples of facilitated transport, the rates of ion movement via an ion channel are roughly 104 - to 105 -fold faster than the rates of molecule movement via a uniporter. What key mechanisticdifference results in this large difference in transport rate?What contribution to free energy (ΔG) determines the direction of transport?