Textbook Question
Which process requires energy—passive or active transport? Why is energy sometimes required to move solute across the cell membrane?
Ch.23 Lipids
McMurry8th EditionFundamentals of GOBISBN: 9780134015187
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Table of contents
- Ch.1 Matter and Measurements27
- Ch.2 Atoms and the Periodic Table20
- Ch.3 Ionic Compounds8
- Ch.4 Molecular Compounds23
- Ch.5 Classification & Balancing of Chemical Reactions12
- Ch.6 Chemical Reactions: Mole and Mass Relationships28
- Ch.7 Chemical Reactions: Energy, Rate and Equilibrium64
- Ch.8 Gases, Liquids and Solids24
- Ch.9 Solutions52
- Ch.10 Acids and Bases25
- Ch.11 Nuclear Chemistry22
- Ch.12 Introduction to Organic Chemistry: Alkanes57
- Ch.13 Alkenes, Alkynes, and Aromatic Compounds47
- Ch.14 Some Compounds with Oxygen, Sulfur, or a Halogen50
- Ch.15 Aldehydes and Ketones45
- Ch.16 Amines42
- Ch.17 Carboxylic Acids and Their Derivatives57
- Ch.18 Amino Acids and Proteins82
- Ch.19 Enzymes and Vitamins63
- Ch.20 Carbohydrates44
- Ch.21 The Generation of Biochemical Energy65
- Ch.22 Carbohydrate Metabolism45
- Ch.23 Lipids42
- Ch.24 Lipid Metabolism33
- Ch.25 Protein and Amino Acid Metabolism24
- Ch.26 Nucleic Acids and Protein Synthesis45
Chapter 23, Problem 75a
Based on the information in Section 23.7, how would you expect each of these common metabolites to cross the cell membrane?
a. CO
Verified step by step guidance1
Understand the nature of the molecule: Carbon monoxide (CO) is a small, nonpolar molecule. Nonpolar molecules can typically diffuse across the lipid bilayer of the cell membrane without the need for transport proteins.
Recall the structure of the cell membrane: The cell membrane is composed of a phospholipid bilayer with hydrophobic (nonpolar) tails facing inward and hydrophilic (polar) heads facing outward. Nonpolar molecules like CO can pass through the hydrophobic core of the membrane.
Apply the principle of simple diffusion: Small, nonpolar molecules such as CO can cross the cell membrane via simple diffusion, which does not require energy or assistance from membrane proteins.
Consider the driving force for diffusion: The movement of CO across the membrane will depend on the concentration gradient. CO will diffuse from an area of higher concentration to an area of lower concentration until equilibrium is reached.
Summarize the process: CO crosses the cell membrane by simple diffusion due to its small size and nonpolar nature, moving along its concentration gradient without the need for energy or transport proteins.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Cell Membrane Structure
The cell membrane is primarily composed of a phospholipid bilayer, which creates a semi-permeable barrier. This structure allows certain molecules to pass through while restricting others based on size, polarity, and charge. Understanding this structure is crucial for predicting how different metabolites, like CO, can traverse the membrane.
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1:00
Cell Membranes Example 1
Diffusion
Diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration. Small, nonpolar molecules, such as carbon monoxide (CO), can easily diffuse across the lipid bilayer of the cell membrane without the need for transport proteins, making this concept essential for understanding CO's movement.
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Transport Mechanisms
Transport mechanisms refer to the various ways substances can cross the cell membrane, including passive transport (like diffusion) and active transport. While CO can diffuse passively, understanding other transport mechanisms is important for comparing how different metabolites might cross the membrane under various conditions.
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Related Practice
Textbook Question
Based on the information in Section 23.7, how would you expect each of these common metabolites to cross the cell membrane?
a. NO (nitrous oxide)
Textbook Question
Based on the information in Section 23.7, how would you expect each of these common metabolites to cross the cell membrane?
c. Ca2+
Textbook Question
Which of the following are saponifiable lipids? (Recall that ester bonds are broken by base hydrolysis.)
a. Progesterone
b. Glyceryl trioleate
c. A sphingomyelin
d. Prostaglandin E1
e. A cerebroside
f. A lecithin
Textbook Question
Identify the component parts of each saponifiable lipid listed in Problem 23.76.
a. Progesterone
b. Glyceryl trioleate
c. A sphingomyelin
d. Prostaglandin
e. A cerebroside
f. A lecithin
Textbook Question
Draw the structure of a triacylglycerol made from two molecules of myristic acid and one molecule of linolenic acid.