This document discusses carbohydrates and their biomedical importance. It defines carbohydrates as compounds with the formula (CH2O)n and describes their classification. Monosaccharides like glucose are important energy sources, while disaccharides like sucrose and lactose are used for energy storage. Polysaccharides starch, glycogen, and cellulose serve structural functions. Glycosaminoglycans are heteropolysaccharides that help structure tissues and facilitate cell-cell interactions. Carbohydrates are essential in many biological processes but certain genetic disorders can impact carbohydrate metabolism.

1. Concept of Biomolecules:
Carbohydrates
Dr. Farhana Atia
Assistant Professor
Department of Biochemistry
Nilphamari Medical College, Bangladesh

2. Carbohydrates
• Carbohydrate means hydrate of carbon
• One mole of C combined with 1 mole of H₂O
• Basic formula (CH₂O)n; n=3/ more
• Carbohydrate may be defined as aldehyde or
ketone derivatives of polyhydric alcohol or
compound that yield these derivatives on
hydrolysis

3. Biomedical importance
• Carbohydrates are widely distributed in plant and
animal
• Provide significant fraction of energy in diet
• Major fuel for the tissue of the mammals in the
form of glucose
• Glucose is the only energy source for RBC &
neuron
• Universal fuel for fetus is glucose
• Storage form of energy in body is glycogen
• Ribose is component of nucleic acid (DNA. RNA)

4. • Serve as cell membrane component & mediate
some form of inter cellular communication as
glycoprotein
• Major component of extra cellular matrix in the
form of GAGs
• Disease associated with Carbohydrates are
– DM
– Galactosemia
– Glycogen storage disease
– Lactose intolerance
Biomedical importance

5. • Sugar derivatives
– gluconic acid, glucuronic acid
– amino sugar - glucosamine
• Glycosidic bond
– The anomeric hydroxyl and a hydroxyl of another
sugar or some other compound can join together,
splitting out water to form a glycosidic bond:
R-OH + HO-R'  R-O-R' + H2O

6. Classification: According to no of sugar unit found on hydrolysis
Monosaccharide Disaccharide Oligosaccharide Polysaccharide
Can not be
hydrolyzed into
simpler
carbohydrate
Condensation
product of 2
monosaccharide
Condensation
product of 3-10
monosaccharide
Condensation
product of >10
monosaccharide
Contain 1 sugar unit
Glucose
Fructose
Galactose
Lactose
Sucrose
Trehalose
Maltose
Maltotriose
Rabinose
Raffinose
Rhamninose
Starch
Cellulose
Glycogen
Inulin
Dextrin
3-7 C atom
Cn(H₂O)n
Cn(H₂O)n-1 Most are not
digested by human
enzyme
Linear/ branched
polymer
Sweet to taste
Soluble in water
Crystalline
Sweet to taste
Soluble in water
Crystalline
Sweet to taste
Soluble in water
Crystalline
Tasteless

7. Classification of monosaccharide
– According to number of C atom
– According to presence of functional group

8. Classification of Polysaccharide
 Depending on type of sugar unit
1. Homo polysaccharide
Contain a single monosaccharide species
– Cellulose
– Starch: (glucose)n
– Glycogen: (glucose)n
– Inulin: (fructose)n
2. Hetero polysaccharide
Contain different monosaccharide species
– Glycosaminoglycans

9. Classification of Polysaccharide
 Depending on identity of constituent monosaccharide
1. Hexosan- contain hexoses
2. Pentosan- contain pentoses
 Food polysaccharide
1. Starch & dextrin
2. Non starch
• Not digested in human
• Cellulose
• Inulin

10. Monosaccharide

11. Disaccharides

12. Importance of Monosaccharides
Sugar Source Importance
Ribose Nucleic acid,
Metabolic
intermediates
Structural component of NA &
coenzymes [ATP, NAD(P), Flavin]
Glucose Fruit juice,
Hydrolysis of
starch,
Cane & beat sugar,
Maltose, Lactose
Main metabolic fuel for tissues,
Sugar carried by blood- ‘Blood
sugar’,
Excreted in urine (glycosuria) in
hyperglycemia (DM)
Converted to glycogen for storage

13. Importance of Monosaccharides
Sugar Source Importance
Fructose Fruit juices,
Honey,
Hydrolysis of
cane/ beat sugar
& inulin,
Glucose for food
manufacture
Readily metabolized (via Glucose/
directly)
Hereditary fructose intolerance 
fructose accumulation &
hypoglycemia,
Gives energy to sperm
Galactose Hydrolysis of
lactose
Readily metabolized,
Synthesized in mammary gland (milk)
Constituents of
glycolipid/glycoprotein
Hereditary galactosemia Cataract

14. Importance of Disaccharides
Sugar Source Importance
Sucrose Cane & beat
sugar,
Fruits, vegetables
Genetic lack of sucraseSucrose
intolerance diarrhea & flatulence
Lactose Milk Alactasia Lactose intolerance
diarrhea & flatulence
Excreted in urine in pregnancy
Maltose Enzymatic
hydrolysis of
starch,
Germinating
cereals & malt

15. Sugar Source Importance
Lactulose Heated milk
Synthetic (mainly)
Not hydrolyzed by intestinal
enzyme, fermented by
intestinal bacteria.
Used as mild osmotic laxative
Starch Food grains, rice
cover, cereal,
potato, legumes,
starchy vegetables
Most important dietary
carbohydrate,
Storage & structural function
(plant)

16. Starch
Called glucosan
Structure-
1. Amylose [13-20%]
– Non branching
– Helical structure
– α14 glycosidic
linkage
2. Amylopectin [80-87%]
– Branched chain
– 24-30 glucose in chain with α14 glycosidic linkage
– α16 glycosidic linkage at branch point

17. Glycogen
• Storage polysaccharide in animal,
often called animal starch
• Present in liver & muscle
• More highly branched than
amylopectin
– 12-14 glucose residue (α14
glycosidic linkage) in chain
– Branchig by α16 glycosidic
linkage
• Muscle glycogen granule contain
up to 60,000 glucose residue

18. Cellulose
• Chief constituent of frame work of plant cell wall
• Insoluble in water
• Straight chain of glucose by β14 glycosidic bond
• Enzyme to hydrolyze this bond is absent in human
• Indigestible part of diet
• Major component of dietary fiber
• Form bulk of stool
• Helps in cholesterol excretion
• Prevent
– Constipation
– Carcinoma of colon

19. Inulin
• Polymer of fructose
• Source- Tubers, garlic, onion
• Not hydrolyzed by intestinal enzyme
• Used in determination of GFR
Dextrin, limit dextrin
• Intermediates in hydrolysis of starch

20. Invert sugar
• A mixture of equal parts of glucose and fructose
resulting from the hydrolysis of sucrose.
• It is found naturally in fruits and honey and produced
artificially for use in the food industry.
• Hydrolysis results in an inversion of the rotation of plane
polarized light
– Fructose: strong levorotatory
– Sucrose: weak dextrorotatory

21. Reducing sugar
• A reducing sugar is any sugar that is capable of
acting as a reducing agent
• Because it has a free aldehyde/ketone group
• Reduce Benedict’s reagent
• All monosaccharide & disaccharide except sucrose
• Sucrose have glycosidic bonds between their
anomeric carbons and thus cannot convert to an
open-chain form with an aldehyde group

22. Glycosaminoglycans/ GAGs/
(Mucopolysaccharides)

23. Glycosaminoglycans
• are a group of high
molecular weight
• linear polymer of repeating
disaccharide unit.
• Each unit: Aminosugar+
Acid sugar (uronic acid)
• Heteropolysaccharide
• Generally associated with
small amount of protein-
proteoglycan

24. Properties
• Negatively charged (carboxy & sulfate groups)
• Special ability to bind large amount of water
• Thereby produce gel like matrix
• Negative charge extend in solution & repel each other
& prevent friction
• Contribute the resilience of synovial fluid & vitreous
humor of eye

25. Types
Hyaluronic acid
Synovial fluid
Vitreous humor
Loose connective tissue
Umbilical cord
Chondroitin Sulphate
Cartilage
Bone
Cornea
Dermatan sulphate
Skin
Blood vessel
Heart valve
Keratan sulphate
1- Cornea
2- Connective tissue
Heparin Mast cell
Heparan Sulphate
Skin
Aortic wall

26. Functions of GAGs
• Structural component of extra cellular matrix.
• Stabilize & support cellular component of
tissue
• Maintain water & salt balance
• Facilitate cell-cell interaction, cell adhesion,
cell migration; act as cell receptor
• Acts as shock absorber & lubricant in joints
(HA)
• Maintenance of compressibility of cartilage
(HA, CS)

27. • Structural role in sclera & role in corneal
transparency (KS, DS)
• Specific interaction with collagen, elastin, & other
proteins in ECM
• Acts as anticoagulant
• Determines the charge selectiveness of renal
glomerulus
• Formation of cell membrane and synaptic vesicles
• Amino sugar of GAGs have antibiotic activity
(Erythromycin)
Functions of GAGs