Aldose and ketose both are monosaccharides. These are different from each other based on the group they contain. The carbon skeleton of aldose has an aldehyde group and is found in plants. At the same time, the carbon skeleton of ketose has a ketone group used in processed foods. Aldose and ketose sugars can be distinguished with the help of Seliwanoff’s test. After the test, the aldose turns into light pink color while ketose turns into a cherry red color.
Let’s take a closer look at aldose vs. ketose sugars
| Description | Aldose is a simple sugar with an aldehyde group, while ketose has a ketone group |
| Chemical purity | Aldose is pure sugar, while ketose is not a pure sugar |
| Chemical formula | The chemical formula of aldose is Cn(H2O)n. and for ketose in RCOR |
Table of Contents
What is Aldose?
Aldose is a simple, pure sugar in which the carbon backbone chain has an aldehyde group. Most of the aldose molecules have a clinical structure and form a six-ring shape. Ribose, glucose, Erythrose, and galactose are examples of aldose. The chemical name of aldose sugar depends upon the number of carbon atoms present in them. It is mostly found in plants, for example, glucose.
What is Ketose?
Ketose is an impure sugar that has a ketone group with the carbon chain. Ketose sugar can also be divided into subcategories depending upon the number of carbon items in the main chain. For example, ketose with three carbon is triose, four carbon is tetrose, and five carbon is pentose. Ketose is mainly found in processed foods like fructose.
Aldose vs. Ketose similarities:
- Both aldose and ketose monosaccharides are simple carbohydrates
- Subcategories of both sugars depend upon the number of carbon items present
- Both have their empirical chemical formula
Seven key differences between aldose and ketose sugars
There are several key differences when comparing aldose vs. ketose sugars:
| Components | Aldose | Ketose |
|---|---|---|
| Groups | Aldose has a carbonyl group on the endmost carbon and a hydroxyl group on all other carbon atoms | Ketose contain ketone group on their carbon chain |
| Sources | Aldose is mainly found in plants. For example glucose | Ketose is mostly present in processed food. For example fructose |
| Isomerization | Aldose can convert into ketose, depending upon the isomerization reaction. | Ketose isomerizes into aldose if the carbonyl group is at the end of the carbon chain. |
| Carbon atoms | Most of the aldose molecules have a cyclical structure, which means they form a six-member ring structure like a hemiacetal ring due to the presence of carbon. | In the ketone group, the carbon atom is always at number 2. And if aldose from the six-member ring, the ketose form a five-member ring just like hemiketal |
| Naming | Chemical naming in aldose depends on the number of carbon atoms present. For example, aldose with six carbon atoms is known as aldohexoses. | The chemical naming of ketose depends on carbon atoms; if a ketose molecule has five carbon atoms, it would be known as ketopentose and so on. |
| Seliwanoff’s Test | In Seliwanoof’s test, aldose responds at a moderate rate and shows a light pink color. | In Seliwanoff’s Test, a reaction between ketose and crystalline compounds results in a deep cherry-red color. |
| Examples | Glucose, galactose, Erythrose, glycolaldehyde, and glyceraldehydes are examples of aldose. | Sorbose, nonoses, pentoses, tetroses, hexoses, etc., are examples of ketose. |
Aldose vs. Ketose Pros and cons
Pros and cons of Aldose
Pros of Aldose
- Glucose, which is aldohexose, is the most important sugar in the human body. It works as a fuel for human cells.
- Aldose reductase reaction is very important for the proper functioning of different organs of our body.
- Glyceraldehydes help the body in making ATP, which is used in different metabolic functions like muscle contraction.
Cons of Aldose
- Galactose present in milk and dairy products can cause diarrhea and stomach problems.
- High level of glucose can cause diabetes and other major health risks.
Pros and cons of Ketose
Pros of Ketose
- Several ketoses play an important role in increasing the body’s metabolism.
- Ketoses are the monosaccharides that work as nucleic acid building blocks.
- Fructose which is one of the ketoses helps in enhancing glucose metabolism.
Cons of Ketose
- A higher amount of fructose can lead to inflammation and other serious health conditions.
- Fructose can also increase the level of bad cholesterol in the body resulting in fat accumulation.
Aldose and Ketose sugar examples
Example of Aldose:
- Glucose
- Galactose
- Erythrose
- Ribose
- Glyceraldehyde
Example of Ketose
- Fructose
- Ribulose
- Erythrulose
- Xylulose
Comparison Chart
Comparison Video
Aldose vs. Ketose FAQ
What is the difference between aldose and ketose?
The main difference between aldose and ketose is that they contain different functional groups.
How do you know if it’s aldose or ketose?
The difference between aldose and ketose can be distinguished with the help of Seliwanoof’s test.
What is aldose in chemistry?
Aldose is a simple sugar that contains the aldehyde group.
What is the structural difference between aldose and ketose?
The structural difference between aldose and ketose is that aldose has an aldehyde group in its structure, while ketose has a ketone group in its structure.
What is a ketose structure?
Ketose has a three-carbon structure. There is one keto group, and the other two are hydroxyl groups.
Why does ketose dehydrate faster than aldose?
In the dehydration of Aldoses, there is an extra step of ring contraction, which decreases the rate of its dehydration. Thus ketose dehydrated faster.
Is lactose a ketose or aldose?
Lactose is not an aldose itself, but it consists of two smaller sugars which both are aldoses.
Why is glucose an aldose?
Glucose is an aldose because it contains aldehyde as its functional group.
How do you identify an aldose or ketose in cyclic form?
Try to find the anomeric center in a cyclic form, and look at the substituents. If one is H, then it is an aldose. The cyclic structure of ketose has a keto group in the second carbon.
Conclusion
Aldose and ketose both are simple carbohydrates and are known as monosaccharides. Both aldose and ketose carbohydrates are different from each other on the basis of their functional group. The structure of aldose and ketose is different from each other as aldose sugar has an aldehyde group in its structure, while ketose has a ketone group in its structure. Glucose and fructose, examples of aldose and ketose, are important sugars in the human body.
