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

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Common Monosaccharides include glucose, galactose, and also fructose. Glucose (C6H12O6) is a typical monosaccharide and crucial source of energy. Throughout cellular respiration, glucose releases power that helps make adenosine tree phosphate (ATP). Tree synthesize glucose making use of carbon dioxide and water, and also glucose, in turn, is used for energy requirements for the plant.

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


Monosaccharides deserve to exist as a direct chain or together ring-shaped molecules; in aqueous solutions, they are uncovered in the ring forms. Glucose in a ring kind can have actually two different 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 ~ above the opposite next from the CH₂OH group in the sugar, it is in the α form. If the is ~ above the very same side together the CH₂OH group, that is in the β form.

Practice Questions

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The framework of monosaccharides

Hemiacetal formation of carbohydrates

MCAT official Prep (AAMC)

Key Points

• Monosaccharides space the building blocks the carbohydrates and also can be classified together aldehydes or ketones.

• Monosaccharides are additionally classified through the variety of carbons in the backbone.

• Glucose, galactose, and fructose space monosaccharide isomers, which way they all have the same chemical formula yet differ structurally and also stereochemically.

• Monosaccharides deserve to exist together a direct chain or together ring-shaped molecules, and also are classified based on the position of your carbonyl.

• Monosaccharides room in the α form when the hydroxyl group is listed below carbon number 1, if they room in the β form when the hydroxyl group is over the plane.

Key Terms

Monosaccharides: The straightforward unit that carbohydrates the cannot it is in hydrolyzed to less complicated chemical compounds v the basic formula (CH2O)n.

Aldehyde (aldose): A compound that has the functional team -CHO, whereby the carbonyl facility is external inspection to a hydrogen and a side team R.

Ketone (ketose): A compound that contains the functional team -RC(=O)R’, where the carbonyl facility is external inspection to 2 side groups R and R’.

Adenosine tree phosphate (ATP): An organic compound that provides energy to cells.

Stereochemistry: The branch the chemistry involved with the three-dimensional arrangement of atoms and molecules and the impact of this on chemical reactions.

Isomer: any type of of two or much more compounds v the same molecular formula however with a different structure.

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