Textbook Question
Classify each of the following monosaccharides by the type of carbonyl group and the number of carbons (for example, a monosaccharide with an aldehyde and three carbons is an aldotriose).
(a) <IMAGE>
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Ch.6 Carbohydrates–Life’s Sweet Molecules
Chapter 3, Problem 17a
Use the structure of d-galactose in Problem 6.15 to answer the following:
(a) Draw the Fischer projection of the carbon 3 epimer.
Verified step by step guidance1
Identify the structure of D-galactose, which is an aldohexose with the configuration of hydroxyl groups on its chiral centers.
Understand that an epimer is a stereoisomer that differs in configuration at only one chiral center.
Focus on carbon 3 of D-galactose, which is the third carbon in the chain, and note the orientation of the hydroxyl group.
To draw the Fischer projection of the carbon 3 epimer, invert the configuration of the hydroxyl group at carbon 3 while keeping the rest of the molecule unchanged.
Ensure that the other chiral centers (carbon 2, 4, and 5) maintain their original configurations as in D-galactose.
Verified Solution
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Fischer Projection
The Fischer projection is a two-dimensional representation of a molecule, particularly useful for depicting the stereochemistry of carbohydrates and amino acids. In this format, the vertical lines represent bonds that are oriented away from the viewer, while horizontal lines indicate bonds that are coming towards the viewer. This method simplifies the visualization of stereoisomers, making it easier to identify and differentiate between various configurations.
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Guided course
0:48
Fischer Projections Example 1
Epimers
Epimers are a specific type of diastereomer that differ in configuration at only one specific carbon atom. In the context of carbohydrates, this means that two sugars can have the same molecular formula and structure, but differ in the arrangement of atoms around one chiral center. Understanding epimers is crucial for distinguishing between different sugars and their biological functions, as even a single change can significantly affect their properties.
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1:26D vs L Enantiomers Example 2
D-Galactose Structure
D-Galactose is a six-carbon sugar (hexose) that is an epimer of D-glucose, differing at the C-4 carbon. Its structure includes a hydroxyl group (-OH) on the left side of the Fischer projection at C-4, while in D-glucose, this group is on the right. Recognizing the specific arrangement of functional groups in D-galactose is essential for accurately drawing its Fischer projection and understanding its relationship to other sugars.
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0:56D vs L Enantiomers Example 1
Related Practice
Textbook Question
Draw the Fischer projection for the enantiomer (mirror image) of each of the following:
(a) <IMAGE>
d-Altrose
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Textbook Question
Classify structures A, B, and C in the figure as being either an enantiomer or a diastereomer of d-galactose.
<IMAGE>
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Textbook Question
Identify the monosaccharide that fits each of the following descriptions:
(a) also referred to as dextrose
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Textbook Question
Identify the monosaccharide that fits each of the following descriptions:
(a) in combination with glucose produces the disaccharide lactose
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Textbook Question
ALLIED Health The sugar alcohol ribitol is a component of the vitamin riboflavin and the energy transfer molecule FAD. Ribitol is formed when the monosaccharide ribose undergoes reduction at carbon 1. Draw the structure of ribitol.
<IMAGE>
d-Ribose
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