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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
- In 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_forwardWhich 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_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_forward
- The 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_forwardWe have seen that biological membranes have both lipid and protein components. How do these two parts combine to produce a biological membrane?arrow_forwardWhich 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_forward
- Which 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_forwardWhich of the following describes the fluid mosaic model of the plasma membrane structure? a. The lipid bilayer is solid at body temperature, thus protecting the cell. b. The phospholipid bilayer is embedded with associated proteins, cholesterol and sugars and has a dynamic arrangement. c. The plasma membrane is composed of two layers of proteins embedded with lipids. d. Phospholipids consist of a polar head and a nonpolar tail made of three fatty acid chainsarrow_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_forward
- Describe the general structure of all cell membranes. What are three types of lipid molecules that are present in the cell membrane? Then describe how the different types of lipid molecules can impact membrane fluidity and they can impact membrane shape.arrow_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_forwardMatch the letters on the diagram below to the correct terms. 1. Glycoprotein E 2. Hydrophilic portion of a phospholipid 3. Glycolipid B 4. Hydrophobic portion of a phospholipid G 5. Peripheral membrane protein F 6. Hydrophobic portion of a transmembrane protein 7. Hydrophilic portion of a transmembrane protein Aarrow_forward
Concepts of BiologyBiologyISBN:9781938168116Author:Samantha Fowler, Rebecca Roush, James WisePublisher:OpenStax College