Final answer:
Monosaccharides in the human body change structure through enzymatic reactions within metabolic pathways like mutarotation and glycolysis. They are also broken down during digestion by hydrolysis, which splits larger carbohydrates into monosaccharides.
Step-by-step explanation:
The structure of a monosaccharide is changed from one form to the other in the human body primarily through enzymatic reactions that alter their chemical bonds and functional groups.
This includes various pathways such as glycolysis, where monosaccharides are phosphorylated and oxidized for energy extraction, or other metabolic pathways where monosaccharides might undergo mutarotation - which is the interconversion between their different isomeric forms.
Glycolysis is a key pathway where such transformations occur, involving steps such as the phosphorylation of fructose-6-phosphate, the oxidation of glyceraldehyde-3-phosphate, and eventual formation of compounds like 3-phosphoglycerate and phosphoenolpyruvate.
As an example, in aqueous solutions, monosaccharides like glucose and fructose exist in equilibrium between linear and cyclic structures due to the reaction of aldehydes and ketones with alcohols, a process called mutarotation. This process is crucial for the functioning of monosaccharides within biological systems.
Furthermore, during digestion, hydrolysis reactions break down carbohydrates by adding water to split larger molecules into monosaccharides, thus facilitating their absorption and subsequent metabolism.