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Introduction: The biological membrane helps to separate the contents of the cell from the outside environment. Besides protecting the cell and maintaining its shape, the membranes play several vital roles. They help in cell signal and transport of molecules in and out of the cell.
Answer to Problem 1TY
Correct answer: The chemical composition of biological membranes can be best described by the statement, “Biological membranes are bilayers of phospholipids with associated proteins and carbohydrates”. Hence, the correct answer is option c.
Explanation of Solution
Reason for correct answer:
The membrane is made up of a bilayer of phospholipids. It can be confirmed by taking a look at the nature of the membrane which is both fluid and rigid. It consists of polar heads of phospholipids on the outside and is made up of hydrophobic tails from the inside. Thus, the membrane is polar from the exterior of the layer and hydrophobic from the interior.
The presence of proteins can be easily detected by the presence of various peripheral proteins and protruded fragments of integral proteins. Also, the receptors and associated structures confirm the presence of glycolipids and glycoprotein (made up of carbohydrate) in the membrane.
Option c. is given as “Biological membranes are bilayers of phospholipids with associated proteins and carbohydrates”.
Biological membranes are composed of bilayer of phospholipids along with the proteins and carbohydrate molecules. Hence, the correct answer is option c.
Reasons for the incorrect answer:
Option a. is given as, “Biological membranes are bilayers of proteins with associated lipids and carbohydrates”.
Biological membranes are composed of bilayer of phospholipids not proteins. The membrane is associated with proteins and carbohydrate molecules. Hence, option a. is incorrect.
Option b. is given as, “Biological membranes are composed of two layers-one layer of phospholipids and one layer of proteins”.
Biological membranes are not made up of a layer of proteins and a layer of phospholipids. Hence, option b. is incorrect.
Option d. is given as, “Biological membranes are composed of equal numbers of phospholipids, proteins, and carbohydrates”.
The protein and carbohydrate content in the biological membrane is very small compared to the phospholipids. Hence, option d. is incorrect.
Option e. is given as, “Biological membranes are composed of lipids with proteins attached to the outer surface”.
The polar ends of the phospholipids make the polar head on either side of the membrane. This is possible due to the presence of polar side chains of phosphate. The lipids lack polar ends and hence it cannot form a membrane. Hence, option e. is incorrect.
Hence, the options a., b., d., and e. are incorrect.
The biological membranes is made up with phospholipids bilayers along with proteins and carbohydrates.
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Chapter 5 Solutions
Biology
- Which of the following statements is (are) consistent with what is known about membranes? (a) A membrane consists of a layer of proteins sandwiched between two layers of lipids. (b) The compositions of the inner and outer lipid layers are the same in any individual membrane. (c) Membranes contain glycolipids and glycoproteins. (d) Lipid bilayers are an important component of membranes. (e) Covalent bonding takes place between lipids and proteins in most membranes.arrow_forwardWhich of the following are essential components of cell membrane? a. Cholesterol b.Phospholipids c.Long chain polyunsaturated fatty acids d.All of the abovearrow_forwardIn a cell membrane, which of the following will be able to freely move from one side of the bilayer to the other. Select one: O a. proteins and glycoproteins O b. glycoproteins and lipids O c. lipids O d. lipids and proteins O e. glycolipids and glycoproteinsarrow_forward
- Which of the following correctly describes the structure of the phospholipid bilayer in plasma membranes? The polar hydrophilic groups of each leaflet face outward, toward the aqueous environment on either side of the membrane. A The non-polar hydrophobic groups of each leaflet face inward, toward each other. The non-polar hydrophilic groups of each leaflet face outward, toward the aqueous environment on either side of the membrane. B The polar hydrophobic groups of each leaflet face inward, toward each other. The polar hydrophilic groups of each leaflet face inward, toward each each other. The non-polar hydrophobic groups of each leaflet face outward, toward the aqueous environment on either side of the membrane. The non-polar hydrophilic groups of each leaflet face inward, toward each each other. The polar hydrophobic groups of each leaflet face outward, toward the aqueous environment on either side of the membrane.arrow_forwardExplain the following statement: The structure of all biomembranes depends on the chemical properties of phospholipids, whereas the function of each specific biomembrane depends on the specific proteins associated with that membrane.arrow_forwardWhich of the following statements is/are incorrect? 1. The cell membrane is purely hydrophobic. 2. Glycerophospholipids have a phosphate derivative group that is known as the polar head group. 3. The individual glycerophospholipid molecules that aggregate become covalently linked to each other to form a lipid bilayer. 4. The interfacial region of a lipid bilayer is polar due to the polar head groups of the lipid molecules that make up the bilayer. O 1 and 3 O 1 only O 2 and 4 O 3 only O 4 onlyarrow_forward
- Which 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_forwardThe cells of plant seeds store oils in the form of droplets enclosed by membranes. Unlike the membranes you learned about in this chapter, the oil droplet membrane consists of a single layer of phospholipids rather than a bilayer. Draw a model for a membrane around an oil droplet. Explain why this arrangement is more stable than a bilayer.arrow_forwardWhich of the following statements is CORRECT about the fatty acid residues in membrane lipids? A. Whole swathes of the membrane have higher saturated residues to increase the overall surface tension. B. There are more unsaturated units to maintain the fluidity of the structure at all environmental temperatures. C. More unsaturated residues are present to increase the melting point of the membrane making it resilient. D. Larger quantities of saturated units are present to maximize stacking and provide effective barrier capacity.arrow_forward
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