Concept explainers
According to the fluid-mosaic model of the plasma membrane,
a. protein and phospholipids form a regular, repeating structure.
b. the membrane is a rigid structure.
c. phospholipids form a double layer, with the polar parts facing each other.
d. proteins are free to move within a double layer of phospholipids.
To determine:
Characteristic features of the fluid mosaic model of the plasma membrane.
Introduction:
The fluid mosaic model is composed of lipid bilayer. The lipid bilayer provides elasticity and fluidity to the membrane. It contains the phospholipid, cholesterol, protein, and carbohydrates. The plasma membrane is amphipathic in nature, in which the hydrophobic tails face each other whereas the hydrophilic region faces the cytosol. There are two kinds of proteins present in the membrane- integral and peripheral membrane proteins.
Answer to Problem 1RA
Correct answer:
The fluid mosaic model of the plasma membrane is that the proteins are free to move within a double layer of phospholipids. Therefore, option (d) is correct.
Explanation of Solution
Explanation for the correct answer:
Option (d) is given that proteins are free to move within a double layer of phospholipid. The fluid mosaic model of the plasma membrane describes the membrane as a combination of phospholipid, cholesterol, and protein which give the membrane the fluid nature. The plasma membrane is not a rigid entity hence allows free movement of integral proteins within the lipid bilayer. Hence, option (d) is correct.
Explanation for the incorrect answer:
Option (a) protein and phospholipid form a regular, repeating structure. The two leaflets of the membrane are asymmetric in nature. Both the leaflets are composed of different proteins and lipids, which give a distinct identity to the membrane. Therefore, option (a) is incorrect.
Option (b) the membrane is a rigid structure. The membrane is not a rigid structure. It is a lipid bilayer which is composed of various phospholipids, cholesterol, and proteins. They are composed of amphiphilic molecules. They have a hydrophilic phosphate and a hydrophobic tail. Therefore, option (b) is incorrect.
Option (c) phospholipid forms a double layer, with the polar parts facing each other. The phospholipid forms a two-layered cell membrane, where the hydrophobic tails face each other and the hydrophilic heads or the polar parts face out. Therefore, option (c) is incorrect.
Hence, options (b), (a), and (c) are incorrect.
Want to see more full solutions like this?
Chapter 3 Solutions
Human Physiology
- Which plasma membrane component can be either found on its surface or embedded in the membrane structure? a. protein b. cholesterol c. carbohydrate d. phospholipidarrow_forwardThe tails of the phospholipids of the plasma membrane are composed of _____ and are _____? a. phosphate groups; hydrophobic b. fatty acid groups; hydrophilic c. phosphate groups; hydrophilic d. fatty acid groups; hydrophobicarrow_forwardWhich of the following statements regarding the selective permeability of the lipid bilayer is FALSE? A. the permeability of the lipid bilayer to different substances varies. B. The lipid bilayer component of the plasma membrane is highly permeable to nonvolatile molecules such as oxygen. C. The more hydrophobic or lipid soluble a substance is, the greater the lipid bilayers permeability to that substance. D. The lipid bilayer component of the plasma membrane is moderately permeable to ions and large, uncharged polar moleculesarrow_forward
- Describe the properties of the three classes of membrane proteins (integral, peripheral, and lipid-anchored) along: A. differences from each other B. variation among themselvesarrow_forwardThe plasma membrane is said to be a fluid-mosaic model because it contains a. waxes suspended within a mosaic of phospholipids.b. a mosaic of proteins suspended within a phospholipid bilayer.c. a polysaccharide mosaic suspended within a protein bilayer.d. a mosaic of phospholipids suspended within a protein bilayer.arrow_forwardWhich of the following best describes an integral membrane protein? A.A protein that has an extracellular domain, a membrane-spanning domain that spans the lipid bilayer of the plasma membrane, and an intracellular domain. B.A protein that peripherally associates with the membrane via ionic interactions another protein embedded in the membrane. C.A protein that is soluble in the cytoplasm. D.A protein that peripherally associates with the membrane via ionic interactions between polar charged amino acids and the polar head groups of the phospholipids in the membrane.arrow_forward
- Which of the following is NOT a function of membrane proteins? a.Regulate the passage of ions b.Act as carrier molecules for various solutes c.Act as anchors or stabilizers for the cell membrane d.Storage of cellular nutrientsarrow_forwardIon channels are formed by a particular kind of membrane protein that allows the passage of a specific ion (or ions) under certain conditions. This type of protein is most likely a(n) a. peripheral membrane protein with additional hydrophobic domains b. integral membrane protein with a transmembrane domain c. a cholesterol-like molecule that is positioned in the phospholipid bilayer d. membrane phospholipid with hydrophilic head group e. soluble enzyme anchored to a scaffolding protein on the cytoplasmic side of the plasma membranearrow_forwardWhich of the following statements describes the function of plasma membranes? I. define the boundaries of the cell and its organelles and act as permeability barriers II. sites for specific biological and chemical functions III. possess transport proteins that regulate the movement of substances into and out of the cell and its organelles IV. contain protein molecules that act as receptors to detect external signals V. provide mechanisms for cell-to-cell contact, adhesion, and communication A. I and III B. I, III, IV C. I, III, IV, V D. I, II, III, IV, Varrow_forward
- Mark the following statements about the plasma membrane as true or false. If a statement is false, correct it to make a true statement. a. _____ Integral membrane proteins generally span the width of the plasma membrane, whereas peripheral proteins are found on only one side of the membrane. b. _____ Cholesterol provides the plasma membrane with stability in the face of changing ion concentrations . c. _____ Membrane cholesterol is vitally important for cell-cell recognition. d. _____ Membrane proteins often function as channels or carriers. e. _____ The overall structure of the plasma membrane is a mosaic with the components locked tightly in placearrow_forwardIndicate whether the following statements are true or false. If a statement is false, explain why it is false. a. All types of cells contain cell walls, but only some cell types possess plasma membranes. b. The distribution of specific lipids to the inner and outer leaflet is asymmetrical, or biased, in plasma membranes. C. Lateral diffusion is the movement of lipids from one layer of the membrane to the other. d. Fatty acids tails are used to embed integral, transmembrane proteins in the plasma membrane.arrow_forwardWhich of the following describes integral membraneproteins?a. They permit water movement only into or out of thecell.b. They transport only large proteins into the cell.c. They extend across the phospholipid bilayer.d. They are attached to the external plasma membranesurfacearrow_forward
- Concepts of BiologyBiologyISBN:9781938168116Author:Samantha Fowler, Rebecca Roush, James WisePublisher:OpenStax College