Aldose and ketose sugars are carbohydrate molecules distinctly different from one another. In this lesson, you’ll learn about these sugars, discovering their unique characteristics and structure.
A Review of Carbohydrates
In the boxing ring to the right we have rough and tumble aldose. And on our left, we have light as a feather ketose! Let the games begin!Okay, that might be a touch dramatic.
Although they may not be battling one another in a boxing ring, there is a match to consider: aldose vs. ketose sugars. Before we dive into the differences between the two, let’s review some basic concepts related to both sugar types.These sugars are referred to as carbohydrates. Carbohydrates are an abundant class of organic compounds that supply energy to our body and are made of sugar units called saccharides. There are two types of carbohydrates: simple and complex.
A simple carbohydrate contains only one or two sugar units. Examples of simple sugars include our friends aldose and ketose. Complex carbohydrates contain a polymer of sugar units. That is, these compounds contain long chains of sugar units linked together. Examples of two different sugars are sucrose (i.
e. simple carbohydrate) and starch (i.e. complex carbohydrates).
It is worth noting that, in general, there are less ketose sugars than aldose sugars. A unique feature of ketose is its ability to act as a reducing sugar, converting itself from a ketose to an aldose. A reducing sugar is a sugar that acts like a reducing agent, donating electrons to another sugar molecule.
Because the carbonyl group is located at the end of its structure, it can function as a reducing sugar and change to an aldose.
Differences Between Aldose and Ketose Sugars
From what we have learned, can you identify the main difference between aldose and ketose sugars? The functional groups in each sugar are different. Aldose contains an aldehyde group, and ketose contains a ketone group.
A great way to remember this difference is to focus on the first letter in each term: ‘a’ is for aldehyde in aldose, ‘k’ is for ketone in ketose. Another difference is the location of the carbonyl group in each structure. The carbonyl group is located in the middle of the structure for aldose sugars. In ketose sugars, it is located on the end.
Whether it is an aldose or ketose, both sugars play amazing biological roles in our body. Just remember the difference in functional groups between both sugars and you can never go wrong with confusing the two.
Aldose and ketose sugars are simple carbohydrates. They are also known as monosacharrides.
An aldose sugar contains an aldehyde functional group in its structure; ketose sugars contain ketone functional groups. Aldose sugars that contain more than three carbon atoms possess stereoisomerism. There are more aldose sugars present than ketose sugars. A unique feature of the aldose sugar is the ability to react with an acid and base to form a cyclic ring.
Ketose sugars can act as reducing agent and convert to aldose sugars. An example of an aldose sugar is glyceraldehyde. Ribulose is an example of a ketose sugar.