Table of contents

1. Matter and Measurements4h 31m
2. Atoms and the Periodic Table5h 23m
3. Ionic Compounds2h 18m
4. Molecular Compounds2h 18m
5. Classification & Balancing of Chemical Reactions3h 17m
6. Chemical Reactions & Quantities2h 27m
7. Energy, Rate and Equilibrium3h 46m
8. Gases, Liquids and Solids3h 25m
9. Solutions4h 10m
10. Acids and Bases3h 29m
11. Nuclear Chemistry56m
BONUS: Lab Techniques and Procedures1h 38m
BONUS: Mathematical Operations and Functions47m
12. Introduction to Organic Chemistry1h 34m
13. Alkenes, Alkynes, and Aromatic Compounds2h 12m
14. Compounds with Oxygen or Sulfur1h 6m
15. Aldehydes and Ketones1h 1m
16. Carboxylic Acids and Their Derivatives1h 11m
17. Amines39m
18. Amino Acids and Proteins1h 51m
19. Enzymes1h 37m
20. Carbohydrates1h 41m
21. The Generation of Biochemical Energy2h 8m
22. Carbohydrate Metabolism2h 22m
23. Lipids2h 26m
24. Lipid Metabolism1h 45m
25. Protein and Amino Acid Metabolism1h 37m
26. Nucleic Acids and Protein Synthesis2h 54m

20. Carbohydrates

D vs L Enantiomers

GOB Chemistry

20. Carbohydrates

D vs L Enantiomers

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1:36 minutes

Problem 11a

Textbook Question

Identify the following monosaccharides as the D- or the L-isomer:
(a)

Verified step by step guidance

Step 1: Understand the concept of D- and L-isomers. These are stereoisomers of monosaccharides that differ in the configuration of the hydroxyl group (-OH) on the chiral carbon farthest from the carbonyl group. In a Fischer projection, D-isomers have the hydroxyl group on the right, while L-isomers have it on the left.

Step 2: Examine the structure of the monosaccharide provided in the image. Locate the carbonyl group (either an aldehyde or ketone) and identify the chiral carbon farthest from it.

Step 3: Determine the position of the hydroxyl group (-OH) on the chiral carbon farthest from the carbonyl group. If the hydroxyl group is on the right side in the Fischer projection, it is a D-isomer. If it is on the left side, it is an L-isomer.

Step 4: Verify the configuration by comparing the structure to standard D- and L-isomer examples, ensuring the orientation matches the definition.

Step 5: Conclude whether the monosaccharide in the image is a D-isomer or an L-isomer based on the position of the hydroxyl group on the chiral carbon farthest from the carbonyl group.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Monosaccharides

Monosaccharides are the simplest form of carbohydrates, consisting of single sugar molecules like glucose and fructose. They serve as the building blocks for more complex carbohydrates and are crucial for energy production in living organisms. Understanding their structure and classification is essential for identifying their isomeric forms.

D- and L- Isomers

D- and L- isomers refer to the two enantiomers of monosaccharides based on the orientation of the hydroxyl group (-OH) on the chiral carbon furthest from the carbonyl group. The 'D' designation indicates that the hydroxyl group is on the right in a Fischer projection, while 'L' indicates it is on the left. This classification is vital for understanding the biochemical behavior of sugars.

Fischer Projection

The Fischer projection is a two-dimensional representation of a molecule that illustrates the arrangement of atoms and functional groups. It is particularly useful for visualizing the stereochemistry of carbohydrates, allowing for easy identification of D- and L- isomers. Mastery of this projection is important for accurately determining the isomeric forms of monosaccharides.

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