The structure of a disaccharide is shown below. Which statement applies?A) The two monosaccharide units are joined by a glycosidic bond.B) The disaccharide contains a peptide bond between its units.C) The two monosaccharides are linked by a phosphodiester bond.D) The disaccharide is formed by the hydrolysis of two monosaccharides.

• A. The disaccharide contains a peptide bond between its units.
• B. The two monosaccharides are linked by a phosphodiester bond.
• C. The two monosaccharide units are joined by a glycosidic bond.
• D. The disaccharide is formed by the hydrolysis of two monosaccharides.

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the structure of a disaccharide. A disaccharide is a carbohydrate composed of two monosaccharide units linked together by a covalent bond. This bond is typically a glycosidic bond, which forms through a dehydration reaction (loss of a water molecule).
2. Step 2: Analyze the options provided. Option A mentions a glycosidic bond, which is the correct type of bond that links two monosaccharides in a disaccharide. Option B mentions a peptide bond, which is found in proteins, not carbohydrates. Option C mentions a phosphodiester bond, which is found in nucleic acids, not disaccharides. Option D incorrectly states that a disaccharide is formed by hydrolysis, which is the process of breaking bonds using water, not forming them.
3. Step 3: Recall the process of disaccharide formation. Disaccharides are formed by a condensation reaction (dehydration synthesis), where a hydroxyl group (-OH) from one monosaccharide reacts with a hydrogen atom (-H) from another monosaccharide, releasing a water molecule and forming a glycosidic bond.
4. Step 4: Eliminate incorrect options based on the above analysis. Peptide bonds (Option B) and phosphodiester bonds (Option C) are not relevant to disaccharides. Hydrolysis (Option D) is the reverse process of disaccharide formation, so it is also incorrect.
5. Step 5: Conclude that the correct answer is Option A, as the two monosaccharide units in a disaccharide are joined by a glycosidic bond, which is consistent with the structure and formation of disaccharides.