Textbook Question
Compare the structures of vitamin A and vitamin C. Which one is water-soluble and which is fat-soluble? What structural features does each have that make one water-soluble and the other fat-soluble?
Ch.19 Enzymes and Vitamins
McMurry8th EditionFundamentals of General, Organic, and Biological ChemistryISBN: 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
McMurry8th EditionFundamentals of General, Organic, and Biological ChemistryISBN: 9780134015187Not the one you use?Change textbook
Chapter 19, Problem 20
Based on the structure shown for retinol (vitamin A) and the names of the two related forms of vitamin A, retinal and retinoic acid, what do you expect to be the structural differences among these three compounds?
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Examine the structure of retinol (vitamin A). Retinol is an alcohol, meaning it contains a hydroxyl group (-OH) attached to its carbon chain. This functional group is key to its classification as an alcohol.
Understand the structure of retinal. Retinal is an aldehyde, which means it contains a carbonyl group (C=O) at the end of its carbon chain. The structural difference between retinol and retinal is that the hydroxyl group (-OH) in retinol is oxidized to form the aldehyde group (C=O) in retinal.
Consider the structure of retinoic acid. Retinoic acid is a carboxylic acid, which means it contains a carboxyl group (-COOH). The structural difference between retinal and retinoic acid is that the aldehyde group (C=O) in retinal is further oxidized to form the carboxyl group (-COOH) in retinoic acid.
Summarize the progression of functional groups: Retinol (alcohol, -OH) → Retinal (aldehyde, C=O) → Retinoic acid (carboxylic acid, -COOH). These changes occur through oxidation reactions, where the functional group is progressively oxidized.
Relate the structural differences to their chemical properties. The presence of different functional groups (-OH, C=O, -COOH) affects the polarity, reactivity, and biological roles of these compounds, making each form of vitamin A unique in its function.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Vitamin A Structure
Vitamin A encompasses several compounds, primarily retinol, retinal, and retinoic acid. Retinol is the alcohol form, characterized by a hydroxyl (-OH) group. Retinal, the aldehyde form, has a carbonyl group (C=O) instead of the hydroxyl group, while retinoic acid, the acid form, contains a carboxylic acid group (-COOH). Understanding these structural differences is crucial for grasping their biological functions.
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Structural Formula Concept 2
Functional Groups
Functional groups are specific groups of atoms within molecules that determine the chemical reactivity and properties of those molecules. In the case of vitamin A compounds, the presence of different functional groups—hydroxyl in retinol, carbonyl in retinal, and carboxylic acid in retinoic acid—affects their solubility, reactivity, and biological roles, such as vision and gene regulation.
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Biological Roles of Vitamin A
Vitamin A plays essential roles in various biological processes, including vision, immune function, and cellular communication. Retinol is crucial for the formation of rhodopsin in the retina, which is vital for low-light vision. Retinal is involved in the visual cycle, while retinoic acid acts as a signaling molecule that regulates gene expression, highlighting the importance of structural variations in their functions.
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1:10Coenzyme A Example 4
Related Practice
Textbook Question
Answer questions (a)–(e) concerning the following reaction:
b. Since hydrogens are removed, the enzyme belongs to what subclass of the enzyme class from part (a)?
Textbook Question
Does the enzyme described in each of the following statements require a cofactor to be active?
c. The presence of K+ does not affect the reaction.
Textbook Question
Vitamins are a diverse group of compounds that must be present in the diet. List four functions of vitamins in the body.
Textbook Question
Which vitamin provides us with each of the following?
b. Coenzyme A
Textbook Question
Answer questions (a)–(e) concerning the following reaction:
a. The enzyme involved in this reaction belongs to what class of enzymes?