The monosaccharide consists of single unit which contains carbon chain of three to six carbon. They can combine through glycosidic bonds to form larger carbohydrates. The main function of monosaccharide is to produce and store energy. Glucose and fructose are the most available monosaccharide in nature.

1. Written by
Sidra Mahmood
BS chemistry
MS biochemistry

2. Some important
monosaccharide

3. • Hexoses include the following:
• Glucose
• Fructose
• Galactose
• Mannose
• These are as described

4. • Also called grape sugar and dextrose.
• Occur widely in nature (in fruits, sugar cane, sugar beats,
dates)
• Also occur in combination with other monosaccharide
forming important disaccharides like sucrose , maltose
etc.
• Combination of large number of glucose units give rise to
polysaccharides such as glycogen.

5. • Glucose is also commercially obtained by hydrolysis of
starch which is a polymer of hundreds or thousand of D-
glucose units.
• Human blood plasma contain normally 70-110 mg
glucose/dL in the fasting condition.
• Under normal condition only traces of glucose can pass
through urin.
• In diabetic patients a large amount of glucose can be
found,

6. • The term blood sugar is used for blood glucose because
glucose represent almost 100% of monosaccharide in
blood.
• On reduction of glucose it form the alcohol sorbitol.
• On being oxidized in vitro glucose give rise to three types
of sugar acids depending on experiments.

7. • Glucose can occur in both in pyranose and furanose
form.
• But the former is more stable and predominant.

8. 1. It is 74% as sweet as sucrose.
2. It is readily fermented by yeast.
3. Utilized by tissues for instant energy.

9. • Physiologically and biomedically, glucose is the most
important monosaccharide. The structure of glucose can
be represented in the following ways
• 1. The straight chain structural formula (Fisher projection).

10. • 2. Cyclic formula (Ring structure or Haworth projection)

11. • Monosaccharide in solution is mainly present in ring form.
In solution, aldehyde (CHO) or ketone (C=O) group of
monosaccharide react with a hydroxy (OH) group of the
same molecule forming a bond hemiacetal or hemiketal
respectively.
• The aldehyde group of glucose at C-1 reacts with alcohol
(OH) group of C-5 or C-4 to form either six membered
ring called glucopyranose or five memberedring called
glucofuranose, respectively.
• However, in case of glucose, the six membered
glucopyranose is much more stable than the
glucofuranose ring. In the case of fructose, the more
stable form is fructofuranose. (as mention eariler.)

12. • Also known as the fruits sugar.
• Obtain from Latin word fructus which means fruits.
• And also called levolose due to levorotation.
• Occur in honey and in plants kingdom in combination
with glucose in sucrose.
• The polysaccharide used in investigating kidney function
yields it on hydrolysis.

13. • Animals tissues also contain it in a small amount.
• Seminal fluid has an appreciable amount of fructose.
• It serve as source of energy for spermatozoa.
• Fructose show mutarotation like glucose.
• The specific rotation of its fresh solution is(-)135.5 degree
which falls after some time to (-)92.3 degrees.

14. • Fructose can occur in pyranose form having 2 to 6rings
as well as in furanose form.
• When free it occur in pyranose form which is levorotatory.
• But in sucrose it occur in furanose form which is
dextrorotatory.
• Sweet of all sugars 173% fermented by yeast.

15. • Occur as a part of lactose molecule when combine with
glucose.
• Also occur in seed coats of legumes.
• It is constituents of glycolipids and glycoproteins.
• It has aldohexoses.
• It is dextrorotatory.
• Exhibit mutarotation.
• 32% as sweet as sucrose.

16. • It differ from glucose only in respect to configuration
around carbon no 4.
• The two sugar which differ from each other around one
carbon atom are called epimers.
• So galactose is an epimer of glucose in respect to carbon
no 4.

17. • It is the part of the molecule of a prosthetic
polysaccharide of many glycoproteins.
• Also present in polysaccharide components of
tuberculoproteins.
• If ingested it is absorbed.
• Body convert it to glucose.
• Show similar chemical reaction to glucose.
• It cannot be differentiated from glucose by osazone test.

18. • It differ from glucose only in configuration around carbon
no 2 in simple word it is an epimer of glucose in respect
to carbon no 2.

19. • These are the monosaccharide containing a chain of five
carbon atoms.
• They occur widely in nature. In plants as well as in animal
kingdom.
• Usually they are the component of polysaccharide of
plants and animals kingdom.
• Ribose is a constituent of a ribonucleic acid of the cell
and of many important substance found in cell like
ATP,GTP,CTP.UTP.NAD+,NADP+,FMN,FAD

20. • And coenzymes.
• All these components are of great importance for all living
organisms.

21. • May be aldoses or ketosis.
• Posses strong reducing properties.
• Form osazone crystals with penylhydrazine.
• With acids they are converted into furfurals.
• Can’t be fermented by yeast.

22. • Ribose and ribulose as phosphate are intermediates in
pentose phosphate pathway of glucose metabolism.
• L-xylulose is an intermediate in uronic acid pathway of
glucose metabolism.
• D-lyxose is found in heart muscles as a component of
lyxoflavin.
• D-arabinose and D-xylose are found in glycoproteins
• Important for herbivorous animals but not in human.

23. • These represent sugars in which oxygen of OH group
has been removed leaving behind H.
• The most important deoxy sugar is pentose sugar termed
as 2-deoxy-D-ribose usually called 2-deoxyribose.
• It is the constituent of deoxyribonucleic acid(DNA).
• This give most of sugar reaction but does not form
osazone.

24. • It is unstable.
• In tissues its presence can be shown by Feulgens
reaction which involves the reaction of 2-deoxyribose
with Schiffs reagents.
• Deoxy hexoses also occur in nature e.g L-fucose in milk
and blood.
• Another deoxyhexose 2-deoxyglucose is used in
research.
• It is taken by tissues like glucose but unlike glucose it is
not metabolized.

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