Glucose and galactose differ in configuration at:

Options

A. C–1
B. C-2
C. C-3
D. C-4

Explanation

To solve the question regarding the difference in configuration between glucose and galactose, we can follow these steps:

### Step 1: Understand the Structures of Glucose and Galactose
- Glucose and galactose are both monosaccharides and have the same molecular formula (C6H12O6). However, they differ in the arrangement of their hydroxyl (OH) groups.

### Step 2: Draw the Structures
- Draw the Fischer projections for both glucose and galactose:
- **Glucose**:
- CHO (carbon 1)
- HOH (carbon 2)
- HO (carbon 3)
- H (carbon 4)
- H (carbon 5)
- CH2OH (carbon 6)
- **Galactose**:
- CHO (carbon 1)
- HOH (carbon 2)
- HO (carbon 3)
- HO (carbon 4)
- H (carbon 5)
- CH2OH (carbon 6)

### Step 3: Identify the Differences
- Compare the structures of glucose and galactose:
- The only difference in the configuration is at the fourth carbon (C4).
- In glucose, the hydroxyl group (OH) at C4 is on the right side, while in galactose, it is on the left side.

### Step 4: Conclude the Relationship
- Since glucose and galactose differ in configuration at the C4 carbon, they are classified as epimers. Epimers are a type of diastereomer that differ in configuration at only one specific chiral center.

### Final Answer
- Glucose and galactose differ in configuration at **C4**.

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