Membrane Transport of Small Molecules and the Electrical Properties of Membranes. The concentration of Ca2+ ions within the vesicle will decrease and the concentration of Mg2+ ions within the vesicle will increase. In contrast, Inh42 is a competitive inhibitor, which implies that the mechanism by which Inh42 works involves its competing for the binding site of TspZ with amino acids. Mg2+ is a charged ion and therefore does not interact well with the hydrophobic hydrocarbon portion of the lipid bilayer. You produce lipid vesicles that contain this Mg2+–Ca2+ pump as the sole membrane protein. Cell biology. The initial connection between Cloudflare's network and the origin web server timed out. Explain your answer. Contact your hosting provider letting them know your web server is not completing requests. He thinks his data support the idea that a protein is required for the uptake of his drug; his supervisor thinks his data show that this drug simply diffuses into the cell. 11-2     You have isolated a bacterial transporter that transports Mg2+ and Ca2+ in opposite directions. 11-6     Recall that the Nernst equation is, For univalent ions at 20°C, the equation reduces to. Specifically, be sure to state whether you think there would be net movement of ions and if so, how the concentrations of the Mg2+ and Ca2+ ions inside and outside the bilayer would change. 11-7     Cells containing the mutant Na+ channel will require more acetylcholine to stimulate muscle contraction. Since Inh31 and Inh42 probably interact with different parts of TspZ, adding both inhibitors will probably have a greater effect of decreasing amino acid uptake than will the addition of either inhibitor alone. This is an example of _____. Each pump transports one Mg2+ ion into the vesicle and one Ca2+ ion out of the vesicle during each pumping cycle and ATP hydrolysis powers this transport, as illustrated in Figure Q11-2. The cookie settings on this website are set to 'allow all cookies' to give you the very best experience. CHAPTER 11. The opening of chloride channels will cause chloride to move into the cell, further reducing the resting potential of the neuron. This means that more acetylcholine-gated cation channels must open to reach the amount of depolarization required to open the mutant voltage-gated Na+ channel. More about Molecular Biology Of The Cell Question Bank in portable document format (PDF) you can enjoy and download here The lab has recently isolated two compounds that bind directly to and act as inhibitors of TspZ; these inhibitors have been named Inh41 and Inh42. 11-4     Bacterial lactose permease is a symporter that uses the H+ gradient to drive the transport of lactose across the plasma membrane. Transport depends on the flipping between two conformational states: one that is inward facing and one that is outward facing. Different types of K+ channels are required to ensure that the frequency of action potentials reflects the magnitude of the combined PSPs. A charged ion will be far less likely than a nonpolar molecule to diffuse across a lipid bilayer. The opening of chloride channels will make it harder for the cell to fire an action potential. If the normal, unmutated version of the protein were used for crystallization studies, different conformational states of the protein might have existed and hindered the crystallization process, which requires the formation of well-ordered crystals containing many copies of a protein in a particular conformation to collect analyzable x-ray diffraction data. Get the latest updates on new products and upcoming sales, Copyright © 2020 | All rights reserved. Contact us and submit your document if you believe any copyright infringement has occurred. 11-8     A neuron can receive inputs from many different presynaptic cells and needs to integrate information about the excitatory postsynaptic potentials (PSPs) and inhibitory PSPs it is receiving. Although O2 is indeed larger than Mg2+, because it is a nonpolar molecule it can diffuse more rapidly than Mg2+ across a lipid bilayer. The ion movement will not significantly change the concentrations outside the vesicle. The movement of ions will create a chemical gradient, but not an electrical gradient, because you are swapping a positive divalent ion for another positive divalent ion. As a result, the web page can not be displayed. He refuses to tell you anything about this drug, except to give you a peek at their data (see Figure Q11-3) regarding the kinetics of uptake of this drug into kidney cells. If you want the Solutions Manual please search on the search box. The equilibrium potential will be negative for K+ ions and positive for Na+ ions. Full file at To characterize how Inh41 works, your friend has discovered that Inh41 does not affect the ability of TspZ to bind amino acid, but instead seems to decrease the rate at which TspZ is able to change its conformation. 11-8     The action potential will last longer (the peak will be broader) because inhibition of the delayed K+ channels will inhibit repolarization of the neuron. A test bank will include the following questions: Membrane Transport of Small Molecules and the Electrical Properties of Membranes, Molecular Biology of the Cell, Fifth Edition. 11-3     Your friend is more likely to be correct: the kinetics of transport seen for the drug is more consistent with transporter-mediated diffusion. Explain your answer. Instantly Access The Test Banks And solutions manual you Need !20% off Discount Code: "lovemystudent". Description. The normal voltage-gated Na+ channel has the characteristics depicted by the solid line in Figure Q11-7. Given this information, would you predict that adding Inh41 and Inh42 together to cells would have a greater effect, a smaller effect, or no effect on TspZ transport compared with the addition of only one of these inhibitors onto cells? All contents are provided by non-affiliated third parties. All copyright item if exist will be removed. For additional problem banks/tutoring for USABO contact either Yilun Du at [email protected] or Varun Mangalick at [email protected] Explain your answer. Another graduate student in the lab has been working on how Inh42 affects TspZ and has determined that Inh42 acts in a manner consistent with its being a competitive inhibitor of TspZ. Both Inh41 and Inh42 seem to reduce amino acid transport 10-fold when added to cells individually.