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**Monosaccharide Structure and Classification:**
– Monosaccharides have the chemical formula (CH2O)n, where n ≥ 3.
– They can be classified by the number of carbon atoms they contain.
Glucose is a hexose used for energy and synthesis of various compounds.
– Ribose and deoxyribose are pentose sugars found in RNA and DNA.
– Monosaccharides with eight or more carbons are rarely observed due to instability.
– Simple monosaccharides have a linear and unbranched carbon skeleton.
– Monosaccharides can be aldoses or ketoses based on the position of the carbonyl group.

**Stereoisomers and Configuration of Monosaccharides:**
– Distinct stereoisomers differ in spatial orientation due to chiral centers.
– Simple monosaccharides have chiral carbons except for the first and last atoms.
– Fischer projection is used to draw the skeletal formula of acyclic monosaccharides.
– D- and L- prefixes indicate the sense of rotation.
– Enantiomers rotate light in opposite directions.
– Glyceraldehyde stereoisomers rotate polarized light.

**Chemical Properties and Occurrences:**
– Monosaccharides play a crucial role in metabolism by providing chemical energy.
Glucose is central in glycolysis and citric acid cycle for energy production.
Maltose is formed from the dehydration condensate of two glucose molecules.
– Monosaccharides are building blocks for disaccharides and polysaccharides.
– Different monosaccharides have varying physical structures and chemical properties.

**Cyclisation and Haworth Projection of Monosaccharides:**
– Monosaccharides switch from acyclic to cyclic form through hemiacetal formation.
– Cyclic forms have five or six atoms in the ring.
– Predominance of cyclic forms in solid-state and solutions.
– Mutarotation changes between α- and β-forms.
– Haworth projection represents the stereochemical structure of cyclic monosaccharides.

**Importance in Biological Processes and References:**
– Monosaccharides are essential for various biological processes, energy production, and storage.
– Understanding monosaccharides is fundamental in biochemistry and nutrition.
– References include McMurry’s ‘Organic Chemistry’ textbook, Collins and Ferrier’s work on monosaccharides, and more.
– External links provide additional information on monosaccharides on Wiktionary.

Monosaccharide (Wikipedia)

Monosaccharides (from Greek monos: single, sacchar: sugar), also called simple sugars, are the simplest forms of sugar and the most basic units (monomers) from which all carbohydrates are built. Simply, this is the structural unit of carbohydrates.

They are usually colorless, water-soluble, and crystalline organic solids. Contrary to their name (sugars), only some monosaccharides have a sweet taste. Most monosaccharides have the formula (CH2O)x (though not all molecules with this formula are monosaccharides).

Examples of monosaccharides include glucose (dextrose), fructose (levulose), and galactose. Monosaccharides are the building blocks of disaccharides (such as sucrose, lactose and maltose) and polysaccharides (such as cellulose and starch). The table sugar used in everyday vernacular is itself a disaccharide sucrose comprising one molecule of each of the two monosaccharides D-glucose and D-fructose.

Each carbon atom that supports a hydroxyl group is chiral, except those at the end of the chain. This gives rise to a number of isomeric forms, all with the same chemical formula. For instance, galactose and glucose are both aldohexoses, but have different physical structures and chemical properties.

The monosaccharide glucose plays a pivotal role in metabolism, where the chemical energy is extracted through glycolysis and the citric acid cycle to provide energy to living organisms. Maltose is the dehydration condensate of two glucose molecules.

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