Concept explainers
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
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- 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_forwardWhich of the following is true about phospholipid bilayers?arrow_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
- Explain 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_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_forward
- Which of the named factors might induce bending of membranes? Select one: O a. Cylindrically shaped lipids O b. Carbohydrates C. Conically shaped proteins O d. Cylindrically shaped proteinsarrow_forwardStatements:(1) Fats and oils have the same general chemical structure.(2) Biological waxes have a three-component “block diagram.”(3) In facilitated transport, a substance crosses a cell membrane with the help of a protein “pump.” a. All three statements are true. b. Two of the three statements are true. c. Only one of the statements is true. d. None of the statements is true.arrow_forwardDefine the following terms: a. lipid bilayer b. fluid mosaic model c. membrane fluidity d. flippase e. floppasearrow_forward
- Which of the following is true about lipid bilayers? A. They are self-forming. B. They are dynamic. C. They are fluid. D. They are permeable. A, C, D only A, B, C only B, C, D only A, B, C, Darrow_forwardA) Briefly describe the basic structure of phospholipids and explain how they can provide an effective barrier against the unregulated movement of molecules into or out of cells. B) Not all phospholipids are identical to one another. Describe two components (parts) of that can be altered to create variation between different phospholipids.arrow_forwardIdentify which lipids are important components of the cellular membrane. SELECT ALL THAT APPLY A. Phospholipids B. Bile Salts C. Fatty Acids D. Cholesterolarrow_forward
- Concepts of BiologyBiologyISBN:9781938168116Author:Samantha Fowler, Rebecca Roush, James WisePublisher:OpenStax College