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Differences between Aldose and Ketose

Differences between Aldose and Ketose

Aldoses and ketoses are two types of sugar molecules. While they both have the same chemical formula—C6H12O6—they have different structures and functions. This post will explore the differences between aldoses and ketoses, including their enzymatic reactions, metabolic pathways, and physiological roles. By understanding the differences between these two types of sugar molecules, we can better appreciate their unique contributions to human health.

What is Aldose?

  • Aldose is a simple sugar molecule that contains just one Aldehyde group. Aldoses are the building blocks of larger carbohydrates such as cellulose, glycogen, and starch. Aldoses can exist in either a linear or ring form, and they can be either Aldohexoses or Aldopentoses.
  • The most common Aldose is glucose, which plays an important role in metabolism. Other Aldoses include fructose, mannose, and Galactose. While Aldoses are essential for proper metabolism, they can also be damaging to cellular membranes.
  • When Aldose molecules bond with proteins in cell membranes, they can cause the proteins to become stiff and less able to function properly. This process is known as Glycation, and it is thought to play a role in the development of diabetes and other chronic diseases.

What is Ketose?

  • Ketosis is a metabolic state that occurs when the body starts to break down fat for energy. Normally, the body uses carbohydrate for energy, but when carbohydrate is in short supply, the body will turn to fat.
  • This process produces ketones, which can be used by the body for energy. Ketosis is often associated with low-carbohydrate diets, such as the Atkins diet, but it can also occur in people who are not following a specific diet. Ketosis can have several benefits, including weight loss and improved mental clarity.
  • However, it can also cause fatigue and headaches in some people. Ketosis is a natural process that occurs when the body is deprived of carbohydrates. It is not inherently dangerous, but it is important to speak with a doctor before starting a ketogenic diet or fasting for an extended period of time.

Differences between Aldose and Ketose

Aldose and ketose are two types of monosaccharides, which are the simplest form of carbohydrates. Aldose has an aldehyde group (-CHO) while ketose has a ketone group (-CO-). Aldoses are reducing sugars because the aldehyde group can be reduced to alcohol.

  • Ketoses are non-reducing sugars because the ketone group cannot be reduced. Aldoses are also known as Alditol while Ketoses are known as Ketitol. The names for these two types of carbohydrates were given based on their structures.
  • Aldoses have their carbonyl group in the end (Aldo = Aldehyde) while ketoses have their carbonyl group in the middle(-CO-) (keto = Ketone). Both aldoses and ketoses can exist in linear or cyclic forms. The most common aldose is glucose while the most common ketose is fructose.
  • Aldoses undergo methylation, dehydration, oxidation-reduction, and epimerization reactions. Methylation is the replacement of -OH with -CH3. Dehydration is the removal of water molecules to form bonds between monosaccharide molecules to form disaccharides or polysaccharides.

Oxidation-reduction is when sugar is oxidized (loses electrons) to form an Aldonic acid or it can be reduced to form an alcohol. Epimerization is when the configuration of one carbon changes from D to L or vice versa. Ketoses only undergo methylation, dehydration, and oxidation-reduction reactions.


Aldose and ketose are two types of sugar molecules. They have different chemical structures, and this affects how they are metabolized in the body. Ketose is more common in nature, and aldose is found in high concentrations in human blood and tissues. understanding the differences between these two sugars can help us to better understand diabetes and other metabolic diseases.

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