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10 Difference Between Aldose And Ketose Sugar (With Examples)

source : vivadifferences.com

10 Difference Between Aldose And Ketose Sugar (With Examples)

A carbohydrate is an organic compound
consisting of carbon, hydrogen and oxygen. Carbohydrates are classified into monosaccharides, disaccharides,
oligosaccharides and polysaccharides. The monosaccharides are the simplest
forms of carbohydrates and are further classified based on the carbonyl group
they contain. Accordingly, monosaccharides are the simplest form of
carbohydrates and may be subcategorized as Aldoses
or ketoses.

What Is Aldose?

An Aldose is a
monosaccharide (simple sugar) with carbon backbone chain with a carbonyl group
on the endmost carbon atom, making it an aldehyde and hydroxyl groups connected
to all other carbon atoms. In organic chemistry, an aldehyde functional group
is defined by the presence of a carbon atom double bonded to an oxygen atom and
single bonded to a hydrogen atom.

Majority of the Aldose molecules are cyclical in structure.
Usually, when molecules have cyclical structures, they form a six-member ring
structure referred to as hemiacetal ring because of the presence of carbon. In Seliwanoff’s test, (where the sample is
heated with acid and resorcinol), Aldoses tend to respond at a moderate pace
and deliver a slow light pink color.

The chemical names of the Aldose sugars depend on the number
of carbon atoms they possess. The minimum number of carbons in a backbone
needed to form a molecule that is still considered a carbohydrate is 3, and
carbohydrates with three carbons are referred to as trioses. The only
aldotriose is glyceraldehyde. The common categories of Aldoses are those with 6
carbons, aldohexoses.

Examples of Aldoses include:

GlyceraldehydeErythroseRiboseGlucoseGalactoseWhat You Need To
Know About Ketose Sugar

Aldose is the monosaccharide that contains
aldehyde group in its structure along with the carbon chain.Aldose structure has one carbon atom.The chemical formula of Aldose is written as Cn(H2O)n.Aldose is a pure sugar.Examples of Aldose are Glycolaldehyde,
glyceraldehydes, erythrose, threose, glucose and galactose .In Seliwanoff’s test, (where the sample is
heated with acid and resorcinol), Aldoses tend to respond at a moderate pace
and deliver a slow light pink color. An Aldose may decompose into Ketose depending on
the isomerization reaction.Aldoses are primarily found in plants. A good
example is glucose.Majority of the Aldose molecules are cyclical in
structure. Usually, when molecules have cyclical structures, they form a
six-member ring structure referred to as hemiacetal ring because of the
presence of carbon.The chemical names of the Aldose sugars depend
on the number of carbon atoms they possess. The minimum number of carbons in a
backbone needed to form a molecule that is still considered a carbohydrate is
3, and carbohydrates with three carbons are referred to as trioses. The only
aldotriose is glyceraldehyde. The common category of Aldoses are those with 6
carbons, aldohexoses.

What Is Ketose?

Ketose is the monosaccharide that contains ketone group
along with the carbon chain. All monosaccharide ketoses are reducing sugars. One
way to chemically identify a ketose from an Aldose is through Seliwanoff’s
test. In this test, Ketoses react with the crystalline compounds whose name is
resorcinol to give a deep cheery-red color. To isomerize a ketose into an
Aldose, Lobry-de Bruyn-van Ekenstein transformation is applied.

Ketoses may be further subcategorized based on the number of
carbon in the main chain. For example, a three-carbon ketose is referred to as
a triose, tetroses are four-carbon ketoses, pentoses are five-carbon ketoses,
hexoses are six-carbon ketoses.

Examples of ketoses include:

Trioses: dihydroxyacetone Tetroses: erythrulose Pentoses: ribulose, xyluloseHexoses: Fructose, psicose, sorbose, tagatoseHeptoses: sedoheptuloseOctoses: D-manno-octuloseNonoses: D-glycero-D-galacto-nonuloseWhat You Need To
Know About Aldose Sugar

Ketose is the monosaccharide that contains
ketone group along with the carbon chain. Ketose structure has three carbon atoms.The chemical formula of ketose is written as
RCOR. An R group is any molecule or atom that can bind to the carbonyl atom
(CO), forming an aldehyde. Ketose is an impure sugar.Examples of ketone are Fructose, ribulose and
xylulose, erythrulose, tagatose, sorbose, pentoses, hexoses, heptoses, octoses,
nonoses, tetroses etc.In Seliwanoff’s test, Ketoses reacts with the
crystalline compounds whose name is resorcinol to give a deep cheery-red color.
Ketose can isomerizes into aldoses only if the
carbonyl group is at the end of the chain. Ketoses can be found in processed foods. A good
example is fructose.The carbon atom in the ketone group always gets
the number 2. If Aldose forms a six-member ring, ketoses, like the fructose
forms a five member ring referred to as hemiketal.The chemical names of the ketose sugars depend
on the number of carbon atoms they possess. If there are five carbon atoms, it
will be referred to as ketopentose and so on.

Also Read: Difference Between Reducing And Non-reducing Sugar

Difference
Between Aldose And Ketose Sugar In Tabular Form

BASIS OF COMPARISON

ALDOSE SUGAR

KETOSE SUGAR

Description

Aldose is the monosaccharide that contains aldehyde group in its
structure along with the carbon chain.
 

Ketose is the monosaccharide that contains ketone group along with
the carbon chain.
 

Number Of Carbon Atoms

Aldose structure has one carbon atom.
 

Ketose structure has three carbon atoms.
 

Chemical Formula

The chemical formula of Aldose is written as Cn(H2O)n.
 

The chemical formula of ketose is written as RCOR.

Chemical Purity

Aldose is a pure sugar.
 

Ketose is an impure sugar.
 

Examples

Examples of Aldose are Glycolaldehyde, glyceraldehydes, erythrose,
threose, glucose and galactose .
 

Examples of ketone are Fructose, ribulose and xylulose, erythrulose,
tagatose, sorbose, pentoses, hexoses, heptoses, octoses, nonoses, tetroses
etc.
 

Seliwanoff’s Test

In Seliwanoff’s test, (where the sample is heated with acid and
resorcinol), Aldoses tend to respond at a moderate pace and deliver a slow
light pink color.
 

In Seliwanoff’s test, Ketoses reacts with the crystalline compounds
whose name is resorcinol to give a deep cheery-red color.
 

Isomerization

An Aldose may decompose into Ketose depending on the isomerization
reaction.
 

Ketose can isomerizes into aldoses only if the carbonyl group is at
the end of the chain.
 

Source

Aldoses are primarily found in plants. A good example is glucose.
 

Ketoses can be found in processed foods. A good example is fructose.
 

Carbon Atom

Majority of the Aldose molecules are cyclical in structure. Usually,
when molecules have cyclical structures, they form a six-member ring
structure referred to as hemiacetal ring because of the presence of carbon.
 

The carbon atom in the ketone group always gets the number 2. If
Aldose forms a six-member ring, ketoses, like the fructose forms a five
member ring referred to as hemiketal.
 

Naming

The chemical names of the Aldose sugars depend on the number of
carbon atoms they possess. The minimum number of carbons in a backbone needed
to form a molecule that is still considered a carbohydrate is 3, and
carbohydrates with three carbons are referred to as trioses. The only
aldotriose is glyceraldehyde. The common category of Aldoses are those with 6
carbons, aldohexoses.
 

The chemical names of the ketose sugars depend on the number of
carbon atoms they possess. If there are five carbon atoms, it will be
referred to as ketopentose and so on.
 

Also Read: Difference Between Monosaccharide, Disacharide And Polysaccharide

Difference Between Ketose and Aldose | Compare the

Difference Between Ketose and Aldose | Compare the – What is the difference between Ketose and Aldose? • Ketoses are monosaccharides with a ketone group. Aldoses are monosaccharides with an aldehyde group. • Ketoses form hemiketal rings and aldoses form hemiacetal rings.An Aldose is a monosaccharide (simple sugar) with carbon backbone chain with a carbonyl group on the endmost carbon atom, making it an aldehyde and hydroxyl groups connected to all other carbon atoms. In organic chemistry, an aldehyde functional group is defined by the presence of a carbon atom double bonded to an oxygen atom and single bondedHere is the answer for the question – What is the difference between an aldose sugar and a ketose sugar?. You'll find the correct answer below What is the difference between an aldose sugar and a ketose sugar? the number of carbons the position of the carbonyl group the position of the hydroxyl groups one …

10 Difference Between Aldose And Ketose Sugar (With – What is the difference between aldose sugar and ketose sugar? 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.Aldose is the monosaccharide that contains aldehyde group in its structure along with the carbon chain, whereas ketose is the monosaccharide that contains ketone group along with the carbon chain.Differences Between Aldose and Ketose Sugars Aldose contains an aldehyde group, and ketose contains a ketone group. 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.

10 Difference Between Aldose And Ketose Sugar (With

What Is The Difference Between An Aldose Sugar And A – Aldose gets defined as the monosaccharide that only has one aldehyde group in each molecule and becomes a pure sugar. On the other hand, Ketose gets defined as a monosaccharide that has a ketone group in each molecule that contains three carbon atoms. Advertisement – Continue Reading Below Contents: Difference between Aldose and KetoseCore Difference Between Ketose and Aldose Aldose is a monosaccharide that has an aldehyde group in each molecule while ketose is a monosaccharide that has a ketone group in each molecule. Aldose structure has one carbon atom while the ketose structure has three carbon atoms Aldose is a pure sugar whereas ketose is an impure sugarSo, for a carbohydrate to be an aldose it needs an aldehyde group and, to be a ketose, it needs a ketone group. In the structures below, the aldehyde and ketone carbonyl groups have a pink highlight. Examples of aldoses are glucose

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Carbohydrates – Epimers, common names | Chemical processes | MCAT | Khan Academy – – [Voiceover] We've spent a
lot of time on the front end of carbohydrates talking about
their stereochemistry, especially of that last chiral center.
And again, it's because
it plays a large role in the biological function
of these molecules. For example, we humans are
enzymatically programmed to break down and digest the D sugars. For that reason I want to
spend at least one last short amount of time trying
to clarify the questions that I originally had when learning about carbohydrate stereochemistry
and nomenclature. First I need to clarify that D and L refer to stereochemistry
but they don't speak to the overall optical
activity of the molecule. As an example let's take
a look at D-threose. D-threose has an aldehyde functional group and it has four carbons,
so it's an aldotetrose. But you can see that the last
chiral center down here has its functional group, this
hydroxyl group on the right side, so it's a D carbohydrate, D threose, but it turns out that there are actually two chiral centers here and whenever we have n chiral centers, whatever number of chiral centers we have, then we have two to the
n possible stereoisomers. And in this case there
are two chiral centers so we have four possible stereoisomers. And it turns out that this
particular stereoisomer actually has an overall optical
activity such that it rotates plane-like counterclockwise,
as opposed to clockwise like you would see with
most R configurations. So even though this is D
it's actually a negative, it gets a negative sign
for its optical activity. So this is D(-)threose, and again it's D because this
lowest chiral center here has an R stereochemistry,
so it's a D carbohydrate. The second big thing I
want to clarify is that it's important to note that
the D and L configurations of a particular carbohydrate
are enantiomers, which means they differ at every chiral
carbon, not just the last one. We can take a look at this
in the case of glucose. Glucose, again, is an
aldehyde carbohydrate so it's an aldose and it's got six carbons,
so it's an aldohexose. And this is the D configuration. The L configuration is
gonna look like this. You can see again it has six carbons. Nothing's changing there. But as we reflect it across
this mirror every single chiral carbon is going
to be the mirror image. So this is L glucose. And again the big thing
that I want to clarify here is that it's not just this
last chiral center down here. It's not just this last chiral carbon that is flipped for the D and L. The D and L glucose are true enantiomers. Enantiomers, which means
that they're complete mirror images; They differ at
every single chiral carbon. Now that being said if the
D-aldohexoses, these glucose, if the D- and L- aldohexoses
are enantionmers, that means that all of the D-aldohexoses have to be diastereomers of each other, because they're not superimposable and they're not mirror images. I know that's confusing
but I've drawn out here all of the D aldohexoses
and we'll take a look at what I'm talking about. We have the D aldohexoses here and there's eight of them that I've drawn. In the case of glucose, up above, I'm gonna flip back up to it for a second. You see that D-glucose and
L-glucose are enantiomers, they differ at every single carbon. Now, all of these are stereoisomers but they differ at maybe just one. They don't differ at every
single carbon from glucose. Here's glucose down here. You can see D-allose, it's just different at this one chiral carbon right here. Or you can see D-galactose up here. The only difference is this
C4 chiral carbon from glucose. What you see is that
these aren't mirror images and they're not superimposable, so all of the D-aldohexoses
are diastereomers. It's the same thing for
all of the L-aldohexoses, they're all diastereomers of each other. And you can carry that
through the ketopentoses, all the D-ketopentoses would
be diastereomers of each other and they would have a
partner in the L-ketopentoses that would be their enantiomer. So again, this is a
terribly confusing idea but I really think the best way would be if you could just pause
the video for a second and take a look at all eight of these and notice where they're different, and notice that they're not different at every single carbon so
they can't be enantiomers. I've said enantiomers and diastereomers too many times already, I'm sure. I mentioned just a minute ago
that glucose and galactose are different only at the C4 carbon. Remember we've got one,
two, three, four, five, six. And similarly with glucose, one, two, three, four, five, six. So the only carbon that
these differ at is the C4, and because they just
differ at one carbon we have a special word for these,
and they're called epimers. Epimers are diastereomers that
differ at one chiral center. That's a vocab word that's
probably going to come up several more times as you look
at carbohydrate chemistry. You can this thought of D
verse L carbohydrates to the next level with
critical thinking if you consider all of the
stereoisomers for an aldohexose. So again we're talking
about aldohexoses right now. How many chiral centers
do these aldohexoses have? We can count. There are one … So one, two, three, four. That's not numbering that, I'm just counting the chiral centers because this carbon up
here, the carbonyl carbon, is double bonded to an oxygen
so it's not a chiral center. And down here this carbon is bound to two different hydrogens so
it's not a chiral center. So all of these aldohexoses
have four chiral centers. That means they have two to
the four or 16 stereoisomers. Half of those are gonna have to have this OH at the bottom on the right side and the other half would be left. So half of 16 is eight and that's how we get to this idea that there are eight D-aldohexoses. That's a thought that you can use and you can translate that into pentoses. Pentoses are gonna have
three chiral centers so there's gonna be ultimately eight, and there would be four D and four L. The last thing I wanna do
is cover the common names for the five most commonly
seen monosaccharides. I've similarly pre-drawn
their structures in and I'll give you their
names and the mnemonics that I was taught to remember them by. The first one that we have right here, number one, is ribose. The way I remember
this, this is a pentose, it's an aldopentose, it's got
an aldehyde and five carbons. It's an aldopentose and
all of the substituents, all of these hydroxyl groups
are on the right side. I remember that ribose is "all right." The next one we have,
hopefully you can see here because we've drawn it
a couple different times is glucose. I should mention that
this is D-glucose, again, and I should mention that
this is D-ribose here. The way that I remember
glucose is actually a little bit racy, so keep
in mind that I do not support flipping people off
with your middle finger, but if you look at this,
man, it sure does resemble somebody flipping off people,
so you can say, I don't know, whatever insult you want to glucose. I'll just write some expletive
marks here to glucose. You can remember that glucose, we'll just pretend that we're
really frustrated with it and we're cursing it out. And again I don't condone
you using your middle finger, but thank goodness that
organic chemistry can redeem even the most heinous of societal insults. We can remember that D-glucose
looks like if we're holding– Kind of, this is our pointer finger, and you can curl your finger up and stick your middle finger out with the fingernail down towards the page and I'm sure you can make the connection of how your fingers resemble glucose. That's my mnemonic for that. This next one is mannose,
and again it's D-mannose. And if you position your fingers in the same way that you were with glucose and now you just extend
your pointer finger as well. Now we've got two fingers
extended and then two curled up. We can see that it's like
a man holding his gun. We're the man and we're holding our gun and that's D-mannose. So man with a gun. And again this is an
aldohexose just like glucose and to keep using that vocabulary these are diastereomers of each other. This next one on the list is galactose. It's kind of lame but
the way I remember this is that D-galactose is
the C4 epimer of glucose. So galactose, I've got
this C4 epimer of glucose. Down here this is the only carbon, the only chiral center where
it differs from glucose so I remember it's the C4 epimer. And then last but not
least we have fructose, and this made an appearance
in an earlier video. We've got D-fructose and the
way I remember D-fructose is that it's the ketose of glucose. So the ketose of glucose, and
you can see that it very much resembles glucose except
that instead of an aldehyde it has a ketone functional group. These are maybe the most common
monosaccharides that you'll see in an organic chemistry
and biochemistry context. .

Reducing Sugars – .

The Aldose Monosaccharides Part 2 – .