Monosaccharides are likewise classified based on the number of carbons in the backbone. Trioses, pentoses, and also hexoses have actually three, five, and six carbon backbones, respectively.

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Common Monosaccharides incorporate glucose, galactose, and fructose. Glucose (C6H12O6) is a usual monosaccharide and crucial source of energy. During cellular respiration, glucose releases power that helps do adenosine tree phosphate (ATP). Tree synthesize glucose making use of carbon dioxide and also water, and also glucose, in turn, is supplied for power requirements because that the plant.

Galactose (a milk sugar) and also fructose (found in fruit) room other typical monosaccharides. Return glucose, galactose, and fructose all have actually the very same chemical formula (C6H12O6), they differ structurally and also stereochemically, which makes them various molecules. They room all isomers that one another, or isomeric monosaccharides. Glucose and galactose space aldoses, and also fructose is a ketose.


Monosaccharides have the right to exist together a straight chain or as ring-shaped molecules; in aqueous solutions, lock are uncovered in the ring forms. Glucose in a ring kind can have actually two various arrangements of the hydroxyl group (OH) approximately the anomeric carbon (this carbon becomes asymmetric in the process of ring formation). If the hydroxyl group is on the opposite next from the CH₂OH team in the sugar, that is in the α form. If it is on the exact same side as the CH₂OH group, that is in the β form.

Practice Questions

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The structure of monosaccharides

Hemiacetal formation of carbohydrates

MCAT official Prep (AAMC)

Key Points

• Monosaccharides room the structure blocks that carbohydrates and also can be classified together aldehydes or ketones.

• Monosaccharides are additionally classified by the number of carbons in the backbone.

• Glucose, galactose, and also fructose room monosaccharide isomers, which method they all have the exact same chemical formula however differ structurally and also stereochemically.

• Monosaccharides deserve to exist together a straight chain or together ring-shaped molecules, and are classified based upon the position of their carbonyl.

• Monosaccharides space in the α type when the hydroxyl group is below carbon number 1, while they room in the β form when the hydroxyl team is above the plane.

Key Terms

Monosaccharides: The basic unit that carbohydrates the cannot be hydrolyzed to simpler chemical compounds with the basic formula (CH2O)n.

Aldehyde (aldose): A link that contains the functional team -CHO, where the carbonyl facility is bonded to a hydrogen and also a side team R.

Ketone (ketose): A compound that contains the functional team -RC(=O)R’, where the carbonyl facility is bonded to two side groups R and also R’.

Adenosine triphosphate (ATP): An organic compound the provides power to cells.

Stereochemistry: The branch of chemistry came to with the three-dimensional plan of atoms and molecules and also the impact of this on chemistry reactions.

Isomer: any type of of 2 or more compounds with the exact same molecular formula but with a various structure.

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Anomeric carbon: A carbon acquired from the carbonyl carbon (the aldehyde or ketone group) the the open-chain kind of the carbohydrate molecule.