Glucose

Glucose is a simple sugar with the molecular formula C6H12O6. Glucose is the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using energy from sunlight, where it is used to make cellulose in cell walls, the most abundant carbohydrate in the world. 

In energy metabolism, glucose is the most important source of energy in all organisms. Glucose for metabolism is stored as a polymer, in plants mainly as starch and amylopectin, and in animals as glycogen. Glucose circulates in the blood of animals as blood sugar. The naturally occurring form of glucose is d-glucose, while l-glucose is produced synthetically in comparatively small amounts and is less biologically active.Glucose is a monosaccharide containing six carbon atoms and an aldehyde group, and is therefore an aldohexose. The glucose molecule can exist in an open-chain (acyclic) as well as ring (cyclic) form. Glucose is naturally occurring and is found in its free state in fruits and other parts of plants. In animals, glucose is released from the breakdown of glycogen in a process known as glycogenolysis. 

Glucose, as intravenous sugar solution, is on the World Health Organization's List of Essential Medicines.It is also on the list in combination with sodium chloride.

Chemical formula :- C₆H₁₂O₆ 

Structure :-

α-d-glucopyranose

Different structure:- 

a) α-d-glucopyranose 

b) β-d-glucofuranose

Chemical properties:-

1.Glucose forms white or colorless solids that are highly soluble in water and acetic acid but poorly soluble in methanol and ethanol.

 2.They melt at 146 °C (295 °F) (α) and 150 °C (302 °F) (β), and decompose starting at 188 °C (370 °F) with release of various volatile products, ultimately leaving a residue of carbon.[22] Glucose has a pK value of 12.16 at 25 °C (77 °F) in water.

3.With six carbon atoms, it is classed as a hexose, a subcategory of the monosaccharides. d-Glucose is one of the sixteen aldohexose stereoisomers. The d-isomer, d-glucose, also known as dextrose, occurs widely in nature, but the l-isomer, l-glucose, does not.

Biochemistry:- 

Metabolism of common monosaccharides and some biochemical reactions of glucose.

Glucose is the most abundant monosaccharide. Glucose is also the most widely used aldohexose in most living organisms. One possible explanation for this is that glucose has a lower tendency than other aldohexoses to react nonspecifically with the amine groups of proteins.[35] This reaction—glycation—impairs or destroys the function of many proteins,[35] e.g. in glycated hemoglobin. Glucose's low rate of glycation can be attributed to its having a more stable cyclic form compared to other aldohexoses, which means it spends less time than they do in its reactive open-chain form.[35] The reason for glucose having the most stable cyclic form of all the aldohexoses is that its hydroxy groups (with the exception of the hydroxy group on the anomeric carbon of d-glucose) are in the equatorial position. Presumably, glucose is the most abundant natural monosaccharide because it is less glycated with proteins than other monosaccharides.[35][36] Another hypothesis is that glucose, being the only d-aldohexose that has all five hydroxy substituents in the equatorial position in the form of β-d-glucose, is more readily accessible to chemical reactions,[37]: 194, 199  for example, for esterification[38]: 363  or acetal formation.[39] For this reason, d-glucose is also a highly preferred building block in natural polysaccharides (glycans). Polysaccharides that are composed solely of glucose are termed glucans.

Key features & importantac:-

Glucose is the most important energy source of carbohydrates to the mammals (except ruminants). The bulk of dietary carbohydrate (starch) is digested and finally absorbed as glucose into the body.

Dextrose (glucose in solution in dextrorotatory form) is frequently used in medical

practice.

Fructose is abundantly found in the semen which is utilized by the sperms for energy. Several diseases are associated with carbohydrates eg, diabetes mellitus, glycogen

storage diseases, galactosemia. Accumulation of sorbitol and dulcitol in the tissues may cause certain pathological conditions eg, cataract, nephropathy.

Inulin, a polymer of fructose, is used to assess renal function by measuring glomerular

filtration rate (GFR). The non-digestible carbohydrate cellulose plays a significant role in human nutrition. These include decreasing the intestinal absorption of glucose and cholesterol, and increasing bulk of feces to avoid constipation.

The mucopolysaccharide hyaluronic acid serves as a lubricant and shock absorbant in

joints The enzyme hyaluronidase of semen degrades the gel (contains hyaluronic acid) around

the ovum. This allows effective penetration of sperm into the ouum.

The mucopolysaccharide heparin is an anticoagulant (prevents blood clotting). The survival of Antarctic fish below -2°C is attributed to the antifreeze glycoproteins.

Streptomycin is a glycoside employed in the treatment of tuberculosis. 

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Biomolecules key features:- Read Know