Dglukoosi

D-glucose, also known as dextrose, is a simple aldohexose and the most abundant monosaccharide in nature. It is a primary source of energy for most living cells and serves as a central metabolic intermediate in glycolysis, the pentose phosphate pathway, and glycogen synthesis. D-glucose is the D enantiomer of glucose, the configuration of the molecule corresponding to D-glyceraldehyde, and it is the form predominantly produced by photosynthesis and found in living organisms.

Chemically, D-glucose has the molecular formula C6H12O6. In solution it exists in cyclical forms, mainly as the pyranose ring, with two anomeric forms, alpha and beta, arising from the opening and closing of the ring (mutarotation). It is a reducing sugar because it contains a free aldehyde group in its open-chain form.

Natural occurrence and physiological role: D-glucose is produced by plants during photosynthesis and is released into the bloodstream through the digestion of carbohydrate-rich foods. In humans, blood glucose levels are tightly regulated by hormones such as insulin and glucagon. Glucose is taken up by cells via specific glucose transporters (GLUT family) and used for energy or stored as glycogen in liver and muscle. It also provides carbon for biosynthetic processes and can be diverted into the pentose phosphate pathway to generate NADPH and ribose-5-phosphate.

Metabolism and applications: In cellular respiration, glycolysis converts glucose to pyruvate, yielding ATP and NADH. Under aerobic conditions, pyruvate is further metabolized in the mitochondria to maximize ATP production. Clinically, D-glucose is used in intravenous solutions and oral rehydration therapies and, in food, as a sweetener and energy source.

Discovery and naming: Glucose was first isolated in the 18th century and the term glucose derives from its sweet nature and chemical characteristics.