Explain. 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. The conformation obtained often reflects the lowest free-energy form of the protein. The cookie settings on this website are set to 'allow all cookies' to give you the very best experience. O2 is bigger than Mg2+ and thus will diffuse more slowly across a lipid bilayer. 1.3 Membrane structure. Molecular Biology of the Cell, Fifth Edition. You produce lipid vesicles that contain this Mg2+–Ca2+ pump as the sole membrane protein. As a result, the web page can not be displayed. Transport depends on the flipping between two conformational states: one that is inward facing and one that is outward facing. Cloudflare Ray ID: 5f8dbb590f230560 This question bank and associated answer sheet were compiled by Yilun Du and Varun Mangalick for. The concentration of Ca2+ ions within the vesicle will decrease and the concentration of Mg2+ ions within the vesicle will increase. Using the C154G mutation that strongly favors the formation of a single conformation facilitated the formation of well-diffracting crystals that allowed the structure to be determined. Additional troubleshooting information here. If a normal cell produces a pattern of membrane depolarization following the combined PSPs illustrated in Figure Q11-8, how would a drug that reduces the activity of the delayed K+ channels alter the pattern of membrane depolarization? 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. View Test Prep - Test-bank-for-Molecular-Biology-of-the-Cell-6th-edition-by-Bruce-Alberts.doc from SCIENCE 2015 at University of Texas. Although O2 is indeed larger than Mg2+, because it is a nonpolar molecule it can diffuse more rapidly than Mg2+ across a lipid bilayer. All copyright item if exist will be removed. From what you have learned in cell biology, who is right: your friend or his supervisor? The opening of chloride channels will cause chloride to move into the cell, further reducing the resting potential of the neuron. 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. Description. 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. For simple diffusion, the rate of diffusion into the cell should be proportional to the solute concentration and should not show a leveling off. 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. In addition, be sure to state whether you would be creating an electrical gradient, a chemical gradient, or both. Membrane Transport of Small Molecules and the Electrical Properties of Membranes. 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. Download Molecular Biology Of The Cell Question Bank free PDF at Info-Nexus. Additional troubleshooting information here. link full download: https://bit.ly/2AI7pgr Language: English ISBN-10: 0815344325 ISBN-13: 978-0815344322 ISBN-13: 9780815344322 Author: Bruce … Explain. This is an example of _____. Contact your hosting provider letting them know your web server is not completing requests. The most likely cause is that something on your server is hogging resources. Get the latest updates on new products and upcoming sales, Copyright © 2020 homeworkmerit.com | All rights reserved. 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. 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. 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. An Error 522 means that the request was able to connect to your web server, but that the request didn't finish. The opening of chloride channels will make it harder for the cell to fire an action potential. 11-7     Cells containing the mutant Na+ channel will require more acetylcholine to stimulate muscle contraction. The most likely cause is that something on your server is hogging resources. Question Type: Multiple Choice 1) The energy stored in ATP is converted to mechanical energy that moves organelles around within the cell. This mutation locked the protein into a particular conformation, so that the transporter was inward-facing such that its sugar-binding domain faced the cytoplasmic portion of the cell. Explain your answer. * Reduces the hassle and stress of your student life. 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. Molecular Biology Problem Set Answers ATP is an important molecule in metabolism because [a] It is readily obtained from an … Both Inh41 and Inh42 seem to reduce amino acid transport 10-fold when added to cells individually. a) being exothermic 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. From the graph, the mutant Na+ channel requires more depolarization of the membrane before ions can flow into the cell. 1.4 … All contents are provided by non-affiliated third parties. The initial connection between Cloudflare's network and the origin web server timed out. 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. Contact your hosting provider letting them know your web server is not completing requests. 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. By inhibiting the delayed K+ channels, the cell will take longer to return to its resting membrane potential, and that is why the peak of the action potential will be broader. You decide to replace this channel with a mutant voltage-gated Na+ channel with the characteristics depicted by the dotted line. Please click Accept Cookies to continue to use the site. Do you predict that the cell containing the mutant Na+ channel will require more, less, or the same amount or acetylcholine to be released from the nerve terminal to stimulate muscle contraction? 11-7     You are interested in understanding how the neuromuscular junction works. 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? To get started finding Molecular Biology Of The Cell Test Bank , you are right to find our website which has a comprehensive collection of manuals listed. Your friend’s experiments show that Inh41 acts as a noncompetitive inhibitor of TspZ, because Inh41 addition decreases Vmax (the rate at which TspZ can flip between two conformational states) and does not seem to affect Km (the affinity of TspZ for amino acids), suggesting that Inh41 does not bind TspZ at its amino acid binding site. Your IP: 70.32.113.56 The Mg2+–Ca2+ pumps are oriented such that Mg2+ is pumped into the vesicle while Ca2+ is pumped out. The ion movement will not significantly change the concentrations outside the vesicle. For additional problem banks/tutoring for USABO contact either Yilun Du at yilundu@yahoo.com or Varun Mangalick at varunm22@gmail.com. Full file at Explain your answer. 11-6     Recall that the Nernst equation is, For univalent ions at 20°C, the equation reduces to. If you were to add a drug that causes the chloride channels on this neuron to open, would this make it easier, harder, or not affect the cell’s ability to fire an action potential? Cell biology. 11-2     You have isolated a bacterial transporter that transports Mg2+ and Ca2+ in opposite directions. • What student Can Expect From A Test Bank? 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.