This Presentation is made for S.Y.Bsc. Students. This presentation includes the Ring structure of monosaccharides and biological significance of Carbohydrate.
2. LECTURE OUTLINE
1 Ring Structure of monosaccharides
2
3
4
Chemical bonds in carbohydrates
Important Polysaccharides
Biological significance
3. Ring Structure of monosaccharides
01
• Pentose form furanose ring
02
Ribose
• Monosaccharides that contain
five or more carbons atoms for
m cyclic structures in aqueous
solution.
• Hexose form pyranose ring
As a result they act as they have extra asymmetric
carbon & have designated α or β
4.
5. Chemical bonds found
A glycosidic bond or glycosidic
linkage is a type of covalent bo
nd that joins a carbohydrate (s
ugar) molecule to another grou
p, which may or may not be an
other carbohydrate.
Glycosidic bond Other bonds
• With PO4 Phosphor ester bond.
• In Amino sugar with Nitrogen C-N
bond.
• With lipids they forms glycolipids.
8. Polysaccharides
Glycogen
Glycogen is a multibranched polysaccha
ride of glucose that serves as a form of
energy storage in animals, fungi, and ba
cteria The polysaccharide structure repr
esents the main storage form of glucose
in the body.
Glycogen functions as one of two forms
of energy reserves, glycogen being for s
hort-term and the other form being trigly
ceride stores in adipose tissue (i.e., body
fat) for long-term storage.
9. Polysaccharides
Starch
Starch is composed of two kinds of polysac
charides, amylose and amylopectin, exclusi
vely composed of D-glucose residues with
α-(1→4) linkages in a linear amylose and
α-(1→4) linkages and ∼5% α-(1→6) branch
linkages in amylopectin, both combined in
a water‐insoluble granule that is partially cr
ystalline and whose size, shape, and morph
ology are dependent on its biological sourc
e.
10. Polysaccharides
Dextran
• Dextran is a complex branched glucan (polysacchar
ide derived from the condensation of glucose). IUPA
C defines dextrans as "Branch d poly-α-d-glucoside
s of microbial origin having glycosidic bonds predom
inantly C-1 → C 6.
• Dextran chains are of varying lengths (from 3 to 200
0 kilodaltons).
• The polymer main chain consists of α-1,6 glycosidi
c linkages between glucose monomers, with branch
es from α-1,3 linkages.
11. Polysaccharides
Cellulose
Cellulose is a polysaccharide compo
sed of a linear chain of β-1,4 linked d
-glucose units with a degree of polym
erization ranged from several hundre
ds to over ten thousands, which is th
e most abundant organic polymer on
the earth.
12. Biological Significance
• Monosaccharides are the major source of fuel for metabolism, being used bot
h as an energy source (glucose being the most important in nature) and in
biosynthesis.
• When monosaccharides are not immediately needed by many cells, they are
often converted to more space-efficient forms, often polysaccharides.
• In many animals, including humans, this storage form is glycogen, especially
in liver and muscle cells.
• In plants, starch is used for the same purpose. The most abundant carbohydr
ate, cellulose, is a structural component of the cell wall of plants and many for
ms of algae.
• Ribose is a component of RNA. Deoxyribose is a component of DNA. Lyxose
is a component of lyxoflavin found in the human heart.
13. Biological Significance
• Ribulose and xylulose occur in the pentose phosphate pathway.
• Galactose, a component of milk sugar lactose, is found in galactolipids in pla
nt cell membranes and in glycoproteins in many tissues.
• Mannose occurs in human metabolism, especially in the glycosylation of cer
tain proteins.
• Fructose, or fruit sugar, is found in many plants and in humans, it is metaboli
zed in the liver, absorbed directly into the intestines during digestion, and fou
nd in semen.
• Trehalose, a major sugar of insects, is rapidly hydrolyzed into two glucose
molecules to support continuous flight.
14. References
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