6. You discover a new transmembrane ion channel and upon structural characterization you demonstrate that it is a homo-tetramer, in which each subunit possess 2 transmembrane a- perpendicular to the plane of the membrane and 20 amino acid residues are embedded in the lipid bilayer. a. Estimate the thickness of the membrane lipid bilayer. b. If the homotetramer has MW of 70 KDa, what percent of its mass would reside in the membrane-spanning portion? c. Upon conformational change one of the two helices in each subunit tilts to 45 degrees within the membrane in respect to the plane. How many amino acids in this helix are embedded in the membrane after the transition? d. What percent of the ion channel mass reside in the membrane-spanning portion after the conformational change occurs? e. Transmembrane pores and channels can also be formed by proteins that form B-barrel structures. B-barrels are constituted by ß-strands that spans the entire membrane. Assuming that these B-strands are perpendicular to the plane of the membrane, how many residues must a B-strand have to span the lipid bilayer? "

6. You discover a new transmembrane ion channel and upon structural characterization you demonstrate that it is a homo-tetramer, in which each subunit possess 2 transmembrane a- perpendicular to the plane of the membrane and 20 amino acid residues are embedded in the lipid bilayer. a. Estimate the thickness of the membrane lipid bilayer. b. If the homotetramer has MW of 70 KDa, what percent of its mass would reside in the membrane-spanning portion? c. Upon conformational change one of the two helices in each subunit tilts to 45 degrees within the membrane in respect to the plane. How many amino acids in this helix are embedded in the membrane after the transition? d. What percent of the ion channel mass reside in the membrane-spanning portion after the conformational change occurs? e. Transmembrane pores and channels can also be formed by proteins that form B-barrel structures. B-barrels are constituted by ß-strands that spans the entire membrane. Assuming that these B-strands are perpendicular to the plane of the membrane, how many residues must a B-strand have to span the lipid bilayer? "

Biology 2e

2nd Edition

ISBN:9781947172517

Author:Matthew Douglas, Jung Choi, Mary Ann Clark

Publisher:Matthew Douglas, Jung Choi, Mary Ann Clark

Chapter5: Structure And Function Of Plasma Membranes

Section: Chapter Questions

Problem 7RQ: A scientist compares the plasma membrane composition of an animal from the Mediterranean coast with...

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Similar questions

1. Researchers have discovered a new membrane protein that has three transmembrane domain αhelixes that span the lipid bilayer. a. If the lipid bilayer is 30 Å thick, what is the smallest number of amino acid residues that can be in each α-helixes for them to be long enough to span the bilayer? b. If one of the three α-helixes is titled at a 32° angle relative to an axis perpendicular to the surface of the lipid bilayer, what is the smaller number of amino acid helixes required for that helix to still span the lipid bilayer? c. How many hydrogen bonding interactions would there be in the smallest possible tilted transmembrane α-helix? d. If the tilted α-helix was a 310 helix instead how many amino acid residues would be required to span the lipid bilayer? How many amino acid residues would be required if it was a π-helix?
17. The transition temperature of a membrane bilayer is determined directly or indirectly a. the ability of lipid molecules to be packed together b. whether the fatty acid chains of the lipids are saturated or unsaturated c. the extent to which the fatty acid chains of the lipids contain double bonds d. the length of the fatty acid chains. e. All of the above are correct answers.
1. When considering tight junctions, adherens junctions, and desmosomes: a. Which ones do not help in resisting mechanical stress and holding cell shape? Why not? b. Considering how the mechanical junctions are placed in the plasma membrane, why don’t they provide a truly sealed barrier?
1. Working as an engineer in the R&D section of a biotech industry, you are asked to select a membrane to concentrate a solution containing a protein with a molecular weight of 200 kDa; Fortunately, it has three types of membrane in the cellar: one for MF, one for UF and one for RO. Which one would you choose to perform the required service? Could you establish some characteristics of the chosen membrane?
Researchers have discovered a new membrane protein that has three transmembrane domain αhelixes that span the lipid bilayer.a. If the lipid bilayer is 30 Å thick, what is the smallest number of amino acid residues thatcan be in each α-helixes for them to be long enough to span the bilayer?
1. Explain in detail how amino acids can be transported across the plasma membrane 2. By using the concept of endomembrane system, explain how plasma membrane involves in the protein synthesis of a cell. 3. With suitable examples, compare the structural and functional differences between a fibrous and globular protein. 4. A person suffers from a skin condition and loss of muscle. A doctor suspects the patient has protein deficiency. Justify why the doctor thinks so.
6. A carrot, when dried out, becomes soft. There is a way to make it firm and crisp. Explain how and why, using the following guidelines. a) Draw and label a representative cell of the carrot, in its dried state. Be precise in your drawing. b)Describe the type of extracellular solution that is appropriate to add to make the desired change (name and define what type of solution, the net movements of solvent and solutes, etc.). c)Draw a representative cell of the carrot, in its possible state after the change. Represent the movement of water using an arrow to indicate what has happened.
19. If a scientist administers an electrical stimulation to a neuronal cell the most likely results will be to a. start a membrane water pump b. cause increased saturation of phospholipid tails c. increase membrane fluidity and lipid asymmetry d. activate the active transport system e. open gated channels
A scientist compares the plasma membrane composition of an animal from the Mediterranean coast with one from the Mojave Desert. Which hypothesis is most likely to be correct? The cells from the Mediterranean coast animal will have more fluid plasma membranes The cells from the Mojave Desert animal will have a higher cholesterol concentration in the plasma membranes The cells’ plasma membranes will be indistinguishable The cells from the Mediterranean coast animal will have a higher glycoprotein content, while the cells from the Mojave Desert animal will have a higher lipoprotein content.
A driving ion moving through a membrane channel in one direction gives energy to actively transport another molecule in the opposite direction. What is this process called? a. facilitated diffusion b. antiport transport c. symport transport d. primary active transport pump e. contransport
3. The protein integrin binds to actin filaments and, by binding to proteins like fibronectins, connects to collagen. In this manner, integrin ______. A.controls the permeability of the cytoplasmic membrane B. suspends organelles within the cytoplasm C. provides a direct linkage between the cytoskeleton and the extracellular matrix D. helps keep individual cells in place and connects adjacent cells to each other
4. The cells making up the epithelial linings of organs that contain liquid, e.g., the bladder and intestines, could be expected to be held together via many ______ in order to provide a waterproof lining. A. tight junctions B. gap junctions C. phospholipids D. intermediate filaments