Biomolecules

As the carbohydrate has six carbons, it is a hexose. Also, it has hydrogen at anomeric carbon (first carbon).

• Anomeric C is the new chiral centre that is formed after cyclization.
• It is the cyclic form of D-glucose.
• As glucose has aldehyde functionality, the structure is aldohexose.

Step 1: Understanding Aspartame

Aspartame is a dipeptide formed by the condensation of aspartic acid and phenylalanine. The methyl ester group is added to the carboxyl group of the phenylalanine residue.

Step 2: Structural Features of Aspartame

• Peptide bond: Formed between the carboxyl group of aspartic acid and the amino group of phenylalanine.
• Methyl ester group: Attached to the terminal carboxyl group of phenylalanine.

Step 3: Verifying the Structure

Structure (B) correctly shows the peptide bond between aspartic acid and phenylalanine, with the methyl ester group on phenylalanine.

Conclusion

The correct structure of aspartame is represented by option (B).

Step 1: Define the Total Number of Monosaccharide Units

The total number of units is given by:

Where:

• : Number of ribose units
• : Number of 2-deoxyribose units
• : Number of glucose units

This equation represents the total count of monosaccharide units in the mixture.

Step 2: Set Up the Molar Mass Equation

Each monosaccharide has a specific molar mass:

• Ribose: 150 g/mol
• 2-Deoxyribose: 134 g/mol
• Glucose: 180 g/mol

The total molar mass of the mixture is 1024 g/mol, leading to:

This equation accounts for the combined molecular weights of all units.

Step 3: Use the Weight Percentage of 2-Deoxyribose

We’re told that 2-deoxyribose constitutes 58.26% of the total weight. The weight of 2-deoxyribose is , and the total weight is . Thus:

Multiply both sides by the denominator to eliminate the fraction:

Calculate the right-hand side:

Rearrange to isolate terms:

Step 4: Substitute and Simplify

From Step 1, we know . Substitute into the equation from Step 3:

Expand the right-hand side:

Combine like terms:

Rewrite for clarity:

Step 5: Solve for Integer Values

To find integer solutions for , , and , test integer values for in the equation .

Try :

Since must be an integer, round to . Then:

Verify with the molar mass equation:

This does not equal 1024, indicating a potential discrepancy. Let’s try another value, e.g., :

This is not an integer, suggesting may need further verification.

Step 6: Final Verification

Using , , :

• Total units: (satisfied)
• Molar mass:
• Weight percentage:

The percentage holds, but the molar mass discrepancy suggests a possible error in the problem setup. The likely number of ribose units is , pending further clarification.

Final Answer: The number of ribose units is .