The parasite Trypanosoma brucei, which causes sleeping sickness, uses proline as an energy sourceduring one stage of its life cycle. The properties of this proline-specific transporter wereinvestigated in a series of experiments. L-hydroxyproline inhibited the transporter. D-proline didnot inhibit the transporter. Na*, K*, and pH changes did not affect the transporter. Which of thefollowing is a reasonable hypothesis based on this data?The proline transporter is a Na+-K+ ion pump.The proline transporter cleaves amide bonds.The proline transporter is stereospecific.The proline transporter requires metal-ion catalysis.The proline transporter has an essential ionizable histidine residue,

A transport mechanism that works to facilitate the movement of substances in and out of the cell…

Answered: The parasite Trypanosoma brucei, which…

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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the sodium channel exchanger NCX transports sodium into and calcium out of cardiac muscle cells. Describe why this itransporter is classified as secondary active transport?
Ion transporters are “linked” together—not physi-cally, but as a consequence of their actions. For example,cells can raise their intracellular pH, when it becomes tooacidic, by exchanging external Na+ for internal H+, usinga Na+–H+ antiporter. The change in internal Na+ is thenredressed using the Na+-K+ pump.A. Can these two transporters, operating together,normalize both the H+ and the Na+ concentrations insidethe cell?B. Does the linked action of these two pumps causeimbalances in either the K+ concentration or the mem-brane potential? Why or why not?
difference between channels and transporters is that O Only channels allow for the passage of solutes against their electrochemical gradient. OTransporters allow for a greater rate of transport across a membrane than channels do. O Only channels allow for the transport of ions. Transporters must undergo a conformational change upon binding to the solute.
The cell membranes of mammalian red blood cells are permeableto urea. If red blood cells are dropped into a solution of urea thatis identical in osmotic pressure (isosmotic) to the cytoplasm ofthe cells, although the cells do not swell and burst as quickly aswhen they are dropped simply into pure water, they eventuallyswell and burst. Explain. Also discuss how you would designa solution into which red cells could be placed without everswelling. (Hint: Think about whether urea will stay on theoutside of the cells and the implications for osmotic pressures.)
Which of the following is CORRECT concerning the ABC transporter proteins? O They do not undergo conformational changes. They are passive transporters. They hydrolyze ATP to produce AMP and diphosphate. They transfer a phosphate to a conserved Asn residue. None of these are correct.
During an investigation on membrane transport, a researcher exposed bacterial cells to different concentrations of two different solutes: A and B. The rate of transport of each solute into cells isrepresented in the graphSolute ASolute BSolute ConcentrationWhich of the following best explains the greater rate of transport for solute A than for solute B at higher solute concentrations?A Solute A is being transported by simple diffusion, which does not rely on membrane proteins to control the rate of transportSolute A is being transported by active transport, which uses ATP and has higher rates of transport than passive transportSolute A is being transported by facilitated diffusion, which uses membrane proteins to increase the rate of transportRate of 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?
Sugars are transported in symport with Na+. Na+ upon some time accumulates causing the need to transport the Na+ back to outside the cell. How is this transport effected so that equilibrium concentrations of electrolytes are maintained in the cells, in accordance with transport in animal cells?
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?
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.
We discussed 3 "directions of movement" categories a transporter can move a molecule (symport, antiport, uniport). Choose TWO directions and 1. provide an example of a transporter or channel type, and 2. describe the direction of movement of a molecule, O doocribe the energy source for the movement of these molecules

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