

What is The Formula For Galactose?
Galactose, which means “milk sugar”, is a monosaccharide sugar. It is an aldohexose, meaning, galactose is a hexose molecule which when represented in a linear manner has carbonyl carbon at position 1 and forms an aldehyde derivative with the following structure: H-C(=O)-(CHOH)5-H. The most common example of such a hexose is glucose with the chemical formula C6H12O6. Now, galactose is a C-4 epimer of glucose which means that it is a diastereomer of glucose centred around the 4th carbon. Hence, the galactose chemical formula can be given as C6H12O6, as galactose and glucose are epimers of each other. Therefore, the galactose formula is the same as the chemical formula of glucose.
Galactose Chemical Formula & Structural Formula
It is now evident to you that the galactose formula of its molecule is the same as that of the glucose molecular formula. Also, it is clear that the galactose structure is an epimer of glucose structure around the C-4 carbon atom in the molecule. Hence, the difference between the galactose structure and glucose structure can be understood from the given Fischer projections (a way of representing the structural formula of a molecule) of both the molecules:
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The above-given form is the linear form of galactose which can be clearly identified by the presence of carbonyl at the end. Galactose molecules can exist either as a linear form or as a ring structure. There are two types of galactose ring structure that you can find. The first one of the galactose ring structure is a six-member ring structure, known as pyranose and the second one is a five-member ring structure known as a furanose. The galactopyranose which is the six-member galactose ring structure is shown below by the Haworth projection.
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The galactose ring structure has four isomers, two of which are the pyranose molecules and two of them are furanose molecules. All of the four isomeric forms of galactose ring structure are given below:
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Understanding from the four given isomeric forms of the cyclic structure, an important characteristic of what is galactose as a monosaccharide, it is important to note that there are two anomeric (geometric variation present at certain atoms present at the carbohydrate molecules) forms of the cyclic structure, the alpha and the beta forms. This is because the transition from the open-chain conformation to the cyclic conformation leads to the creation of a new stereocenter at the place of the carbonyl present in the open-chain conformation. A significant difference in-between the beta form and the alpha form of the cyclic structure is that the alcohol group is present in the equatorial position in the beta form whereas the same alcohol group is present in the axial position in the alpha form.
Hence, when someone asks you what is galactose, you can answer it by giving and explaining the chemical formula galactose is represented by and explaining the relation between glucose and galactose molecule. Also, the structural configurations of the galactose structure are significant in defining what is galactose and what are its chemical properties.
Properties of Galactose
The following are some of the properties of the galactose molecule:
When combined with glucose, it gives a disaccharide molecule, which is known as lactose which also means “milk sugar”.
It is about as sweet as glucose (same structure and chemical properties due to them being epimers of each other) and approximately 65% as sweet as sucrose.
Galactan is the polymeric form of galactose which is also a class of naturally polymeric carbohydrates. It is usually found in hemicellulose.
Glucose is more stable than galactose and hence does not form glycoconjugates (molecules having at least one sugar attached to a protein or a lipid) like galactose. This is thought to be the reason that the pathway of conversion from galactose to glucose in the cells is conserved across all species.
Galactose can be mostly obtained from dairy products, avocados, sugar beets, other gums and mucilages.
Following are Some of The Clinical Significance of Galactose That is Given Below:
Continuous long time exposure to D-galactose of mice, rats and Drosophila have been shown to lead to an acceleration in ageing.
It is a component of the antigens that are present on the red blood cells which are responsible for the determination of the blood group in the ABO blood group system. In the cells identified having O and A antigens, there are two monomers of galactose present on the antigens. On the other hand, the cells having B antigens are known to have three monomers of galactose present on the antigens.
A disaccharide made up of two units of galactose which is known as alpha-gel, is recognised to be the potential allergen that is present in the mammal meat.
Previously, it was thought that there was some linkage between ovarian cancer and galactose metabolism, but more recent scientific studies have found that this is not the case and there is no link in-between the two whatever be the condition of the galactose metabolism pathways.
FAQs on Galactose Formula
1. What is Galactose Made of?
Ans: Galactose is a monosaccharide molecule. It is a stereometrically related form of glucose and hence has the same chemical and molecular formula as glucose and is made of the same hydrocarbons as glucose. Hence, the chemical formula of galactose is C6H12O6. The meaning of the name galactose is “milk sugar” and can be found in milk. When galactose and glucose combine together they form a disaccharide known as lactose which is the most commonly known “milk sugar”.
2. What is the Difference Between Glucose and Galactose?
Ans: Both glucose and galactose have the same molecular formula which is C6H12O6. This is because both glucose and galactose are epimers of each other. Hence, galactose is as sweet as glucose. But there are some differences such as galactose has a higher melting point than glucose. Although both of them have the same sweetness, sometimes galactose appears to be sweeter than glucose on tasting, yet both of them are less sweet when compared to sucrose or table sugar.

















