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In the fluid mosaic model:
plasma membrane proteins orient their hydrophilic sides toward the internal bilayer.
phospholipids often flip-flop between the inner and outer layers.
the mosaic refers to proteins attached to the underlying cytoskeleton.
the fluid refers to the phospholipid bilayer.
the mosaic refers to the symmetry of the internal membrane proteins and sterols.
Introduction:
The membrane of the cell is composed of the phospholipid bilayer and proteins. The structure of the membrane is explained by the fluid-mosaic model proposed by Singer and Nicolson. The proteins are distributed unevenly in the bilayer of the lipids.
Answer to Problem 1TYK
Correct answer:
The fluid in the fluid-mosaic refers to the bilayer of phospholipids.
Explanation of Solution
Explanation for the correct answer:
Option (d) is given that thephospholipid bilayer is the fluid part of the membrane. The cellular membrane is formed of the phospholipids and proteins. The fluidity of the membrane is imparted by the phospholipid bilayer, which is amphipathic in nature. Hence, option (d) is correct.
Explanation for the incorrect answers:
Option (a) is given that the hydrophilic sides of the membrane proteins are present towards the internal layer. The proteins present in the membrane are hydrophilic in nature and are present towards the cytosolic or outer sides. They are attracted towards water and span the membrane. So, it is an incorrect option.
Option (b) is given that phospholipids often flip-flop in the layer. The phospholipid layer of the membrane is continuous and uniform. The lipid molecules move sideways rather than flip-flop movement across the inner and outer sides of the membrane. So, it is an incorrect option.
Option (c) is given that the protein attached to the cytoskeleton forms the mosaic part. The mosaic portion of the membrane is formed by the protein. Proteins span the membrane and are present on both the outer and inner sides of the membrane. The inner proteins are attached to the cytoskeleton. So, it is an incorrect option.
Option (e) is given that the mosaic is formed by the symmetry of the internal proteins and sterols. The mosaic region comprises the total proteins present in the membrane. Proteins are unevenly distributed in the membrane. So, it is an incorrect option.
Hence, options (a), (b), (c), and (e) are incorrect.
Therefore, it is concluded that the fluid part of the membrane is formed by the phospholipid bilayer, while the mosaic region is formed by the total protein of the membrane.
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Chapter 5 Solutions
Biology: The Dynamic Science (MindTap Course List)
- Below are listed molecules with different chemical characteristics. Knowing that all molecules will eventually diffuse across a phospholipid bilayer, select the list that most accurately predicts the relative rates of diffusion of these molecules (fastest to slowest) across a biological membrane. alanine, propanol, sodium, estrogen sodium, propanol, alanine, estrogen estrogen, propanol, sodium, alanine estrogen, propanol, alanine, sodiumarrow_forwardWhich of the following statements is true about biomembrane? Membrane proteins and lipids are distributed symmetrically in the two leaflets of the bilayer. Lipid-linked proteins are anchored to the bilayer by the lipid moiety that covalently attached to the protein. Lipid molecules can diffuse laterally in each leaflet of the bilayer but they can never flip from one leaflet to another. The fluid mosaic model describes the dynamic arrangement and interaction of proteins but not lipids in membrane. Bilayers are formed by triacylglycerol, glycerophospholipids, and sphingolipids.arrow_forwardFill in the blanksarrow_forward
- Besides lipid molecules, cell membranes also contain many different types of proteins, each with specific functions. In the following table, select the common type of membrane protein in the right-hand column that each statement in the left-hand column describes. The choices on the Type of Membrane Protein are the same for theFunction of the Membrane Proteinarrow_forwardWhich of the following describes the plasma membrane? 1) phospholipid bilayer surrounding the cell 2) a membrane composed of tiny shelves or cristae 3) single-layered membrane that surrounds the nucleus of the cell 4) double layer of protein enclosing the plasmaarrow_forwardAccording to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids? They frequently flip-flop from one side of the membrane to the other. They have hydrophilic tails in the interior of the membrane. They can move laterally along the plane of the membrane. They are free to depart from the membrane and dissolve in the surrounding solution.arrow_forward
- Which of the following statements related to intercellular junctions is false? Cadherins are important cell-cell adhesion proteins. A cadherin-mediated junction involves many cadherin molecules to achieve strong adhesion. The cytoplasmic domain of cadherins interacts with actin or intermediate filament cytoskeleton through adaptor proteins. Because tight junctions seal the membrane of adjacent epithelial cells, transmembrane proteins in the apical portion of the plasma membrane cannot move to the basal lateral domain or vice versa. Proteins can diffuse through an open gap junction.arrow_forwardThe cytoplasm of a certain cell is composed of a solution that is 98% water, 2% solutes. Consider the solution shown in the beaker in this picture: FOOE OOS Foor solution. [Select] Cytoplasm is 98% water, 2% solutes. The solution in the beaker would be considered when compared to [Select] The plasma membrane is impermeable to solutes. Beaker solution is 98% water, 2% solutes the cell. We would expect that the cell would [Select] if it was placed in the would account for whatever changes might occur to the volume of the cytoplasm of the cell when it is placed in the solution.arrow_forwardIdentify the basic structure of the plasma membrane. Label the diagram: What are the components of the plasma membrane? Outside the cell Inside the cell Polar head - Nonpolar tailarrow_forward
- Which of the following molecules may diffuse freely through a phospholipid bilayer? (select two answers) asparagine, an amino acid with a large, hydrophilic side chain alanine, an amino acid with a small, hydrophobic side-chain testosterone, a steroid hormone fructose, a monosaccharide molecular oxygen (O2)arrow_forwardThe fluid mosaic model of the membrane describes the membrane as: containing a significant quantity of water in the interior composed of fluid phospholipids on the outside and protein on the inside composed of proteins on the outside and phospholipids on the inside made of proteins embedded into a fluid phospholipid bilayerarrow_forwardGolden Line:Rationale: (Tell me why the authors put this diagram here. What do you think is its main purpose for being in our textbook?)Personal Connection:Question:arrow_forward
Biology: The Dynamic Science (MindTap Course List)BiologyISBN:9781305389892Author:Peter J. Russell, Paul E. Hertz, Beverly McMillanPublisher:Cengage Learning