MCAT Practice Exam – Complete Prep Resource 2026

The formation of a disaccharide primarily involves the process of linking two monosaccharides through a glycosidic bond, which is achieved through a condensation reaction. This process typically entails several key steps.

Initially, one sugar molecule (the anomeric carbon) is activated, allowing it to undergo a nucleophilic attack by the hydroxyl group of the other sugar. This interaction leads to the formation of a covalent bond between the two sugars while concurrently leading to the loss of a water molecule, indicative of a condensation reaction. Additionally, there may be an initial protonation step to facilitate this reaction, often involving the adjustment of the molecular structure to enable the nucleophilic attack.

The loss of the water molecule is a hallmark of condensation reactions, and this critical step results in the formation of the glycosidic bond, which firmly links the two monosaccharides into a disaccharide. Each of these steps is essential for the proper formation of disaccharides, making the detailed sequence in option B relevant and accurate in depicting the overall process.

Understanding this multi-step process is crucial for grasping how carbohydrates are formed and how their structures contribute to biological functions. Disaccharides serve as important intermediates in carbohydrate metabolism and play