Final answer:
The three important monosaccharides are D-glucose, D-fructose, and D-galactose, while the three key disaccharides are sucrose, lactose, and maltose, each pivotal for human nutrition and energy supply.
Step-by-step explanation:
The three monosaccharides of nutritional importance are D-glucose, D-fructose, and D-galactose. These are single sugar molecules known for their role as basic energy units for the body. D-glucose and D-galactose are classified as aldohexoses, while D-fructose is a ketohexose. All three contain six carbon atoms, thus referred to as hexose sugars.
The three disaccharides of significance in our diet include sucrose (table sugar), lactose (milk sugar), and maltose (malt sugar). Sucrose is composed of glucose and fructose, lactose is made of glucose and galactose, and maltose consists of two glucose units. Disaccharides are paired monosaccharides joined by a glycosidic bond, which are broken down into their monomer units by hydrolysis during digestion.