The document discusses the structure of monosaccharides, specifically outlining two representations: straight chain (open chain) and cyclic structures. The straight chain structure, proposed by Fischer, arranges carbon atoms in a line with specific functional group placements, while the cyclic structure, devised by Haworth, forms a ring that can be further classified into furanose and pyranose rings. Furanose is a pentagonal ring comprised of four carbon atoms and one oxygen atom.

1. STRUCTURE OF MONOSACCHARIDES
Dr. P. Japamalai
Maris Stella College
Vijayawada - 8

2. Structure of Monosaccharaides
The Monosaccharide may be represented by two
Structure. They are :
1. Straight chain structure or open chain structure.
2. Cyclic structure or ring structure.
1. Straight chain structure or open chain structure.
 In straight chain structure , the 6 carbon atoms of glucose
are arranged in a straight line.
 It is also called open chain structure because the two ends
remain separate and they are not linked.

4.  Fisher proposed another straight chain structure .
 The straight chain proposed by by Fisher is called as
fisher’s projection formula.
 According to Fisher, the aldehyde group is placed at
one end and the remaining carbon atoms are arranged
one behind the other.
 The last carbon atoms contains two hydrogen atoms
and one OH group .
 The remaining carbon atoms contain H atom on one
side and OH group on other side.

6. .
2.Cyclic structure or Ring structure
 In cyclic structure, the atoms are arranged in the form
of ring.
 Haworth (1929) an English Chemist, devised the ring
structure.
 Hence the ring structure is referred to as Haworth’s
projection formula.
 The sugar molecules exist in two types of rings.
 They are furonose ring and pyranose ring .

8. Furanose Ring
 Furanose is a –membered ring. It is a pentagonal ring .
 It resembels the ring of a compound called furan and
hence called furan and hence it is called furanose ring.
 The furonose ring is formed of 4 carbon atoms and one
Oxygen.

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