full lecture of carbohydrate

1. CARBOHYDRATE
CHEMISTRY

2. • Definition:
• Carbohydrates are Aldehyde or ketone
derivatives of polyhydric alcohols.

3. Functions
1. Carbohydrates are the main sources of energy in the body. Brain
cells and RBCs are almost wholly dependent on carbohydrates as
the energy source. Energy production from carbohydrates will be 4 k
calories/g (16 k Joules/g).
2. Storage form of energy (starch and glycogen).
3. Excess carbohydrate is converted to fat.
4. Glycoproteins and glycolipids are components of cell
membranes and receptors.
5. Structural basis of many organisms: Cellulose of plants;
exoskeleton of insects, cell wall of microorganisms,
mucopolysaccharides as ground substance in higher organisms.

4. • 6-Composed of large portions of the nucleotides
that form DNA and RNA.
• 7-Play a role in lubrication,cellular
intercommunication and immunity.
• 8-Component of blood groups in the blood.

5. • They are classified as follows:
• 1-Monosaccharides are those
carbohydrates that cannot be hydrolysed
into simpler carbohydrates .

6. Simple Sugars -

10. • 2.Disaccharides produce 2 molecules of
monosaccharide on hydrolysis.
• Examples:
• Maltose= Glucose+Glucose
• Sucrose=Glucose+Fructose
• Lactose=Glucose+Galactose.

11. Disaccharides

12. • 3-Oligosaccharides produce 3-10
monosaccharide units on hydrolysis.
• E.g Maltotriose.
• 4-Polysaccharides produce more than 10
molecules of monosaccharides on
hydrolysis.
• E.g Starches and dextrins.

13. • Glucose is the most important
monosaccharide in humans.
• Glucose is represented in three ways:
• 1-Straigh chain form.
• 2-Haworth projection.
• 3-Chair form.

16. Sugars show various forms of
Isomerism.
• Stereoisomers are compounds that have
the same structural formula but differ in
spatial conformation.
• Isomers are formed due to presence of
asymmetirc carbon atoms.
• Number of Isomers=2 to power n.
• N= number of asymmetrical carbon atoms.

17. • Glucose has 4 asymmetrical carbon atoms
• Isomer=16.
• 1-D&L isomerism.
• 2-Optical isomer.
• This is when a beam of polarised light is passed
through a solution and is rotated to:
• A-Right,dextrorotatory(+) or
• B-Left,levorotatory(-)

19. • Racemic:
• This when equal amounts of D and L isomers are
present resulting to mixture of no optical activities.
• 3-Pyranose and Furanose ring structures.
• 4-Alpha and Beta anomers.
• Anomeric carbons are new asymmetric carbons at
C1(glucose) and C2 (fructose) that created by cyclization
at carbon bound to oxygen in hemiacetal formation.
• If the hydroxyl on the anomeric carbon is below the
plane of the ring,it is in the alpha position.
• If the hydroxyl on the anomeric carbon is above the
plane of the ring,it is in the beta position.

21. • Ring structure of Aldose is hemiacetal.
• Hemiacetal= Alcohol+Aldehyde
• The ring structure of ketose is hemiketal.
• Hemiketal=Alcohol+ketone.
• Mutarotation is the equilibrium between
alpha and beta anomers of glucofuranose.
• Glucose is called dextrose because in
solution in the body it exist in
dextrorotatory.

22. • 5-Epimers:
• These are isomers that differ as a result of
variations in the conformation of the-OH
and-H on carbon atoms 2,3, and 4 of
glucose.
• E.g Mannose is an epimer of glucose at
carbon number 2 and Galactose is an
epimer of glucose at carbon number 4
• 6- Aldose and Ketose isomers.

25. Glycosidic linkage.
• Sugars form glycosides.
• Glycosides are compounds formed from a condensation
between the hydroxyl group of the anomeric carbon of a
monosaccharide or monosaccharide residue and a
second compound.
• When second compound is not monosaccharide=
aglycone.
• If it is a hydroxyl an O-glycosidic bond is an acetal link.
• If it is a glucose=glucoside
• If galactose=galactoside.
• If the second group is an amine=N-glycosidic bond.

26. • Glycosides are found in drugs and spices
and animal tissues.
• Aglycone may be:
• Methanol,glycerol,asterol,phenol e t c.
• Important glycosides in medicine are:
• Derivatives of digitalis
• Strophanthus e.g ouabain.
• Antibiotic like streptomycin.

27. Physiologically important glycosides
1. Glucovanillin (vanillin-D-glucoside) is a natural substance that
imparts vanilla flavour.
2. Cardiac glycosides (steroidal glycosides) : Digoxin and
digitoxin contain the aglycone steroid and they stimulate muscle
contraction.
3. Streptomycin, an antibiotic used in the treatment of
tuberculosis is a glycoside.
4. Ouabain inhibits Na+ – K+ ATPase and blocks the active
transport of Na+.
5. Phlorizin produces renal damage in experimental animals.

28. Disaccharides.
• 1-Maltose=Glucose+Glucose.
• The glucose are linked by alhpa 1-4 glycosidic
bonds.
• 2-Sucrose=Glucose+ Fructose.
• The glucose is linked to fructose by beta 1-2
glycosidic bond.
• Hydrolysis of Sucrose produces a crude mixture
called INVERTED SUGAR.In this sugar fructose
under goes a rotation of 180 degrees and then it
is inverted upside down.

30. • Lactose=Glucose +Galactose.
• The link between glucose and galactose is
beta 1-4 glycosidic bond.

34. Polysaccharides.
• Homopolysaccharides are made of the
type of monosaccharide.
• Heteropolysaccharides are made up of
different types of monosaccharides.
• Important in humans as a source of bulk in
the diet.

35. • Starch is a homopolymer of glucose.
• It is formed of alpha glucosidic chain.
• The homopolymer is known as glucosan
or glucan.
• It hydrolysis to glucose.
• Food sources:
• Cereals,potatoes,legumes and other
vegetables.

36. • Starch is storage polysaccharide in plants.
• Starch is made up of :
• A-Amylose-15%-20% and non branching
helical structure.
• B-Amylopectin-80%-85% and consist of
branched chains of 24-30 glucose
residues linked by 1-4 linkage in chain and
1-6 linkage at branching points.

38. • Glycogen is the storage polysaccharide in
animals.
• More branched with 12-14 glucosyl
residues in the chains in alpha 1-4
glycosidic bonds and alpha 1-6 glycosidic
linkage at the branching points.

40. • Inulin is the starch found in the tubers and
roots of Dahlias,Artichokes,and
dandelions.
• Hydrolysis to fructose and therefore it is a
FRUCTOSAN.
• It is soluble in warm water and it is used to
determine the rate of glomerular
filtration(Kidney function).

41. • Dextrins are substances formed during
hydrolysis of starch.
• Limit dextrins are the first formed products
as hydrolysis reach certain degree of
branching.

42. • Cellulose is the chief constituent of the
framework of plants.
• Composed of chains of D-glucose units
linked by B-1-4 glycosidic linkages.
• Chains are linear.
• Cellulose cannot be digested by humans
of lack of hydrolase enzyme that can
break the B linkage.

43. • Chitin:
• Structural polysaccharide of invertebrates.
• Found in the exoskeletons of insects and
crustaceans.
• It consist of N-acetyl-D-glucosamine units
joined by beta (1-4) glycosidic linkage.

45. CARBOHYDRATE DERIVATIVES.
• 1-Phosphoric acid esters of
monosaccharides.
• These are formed from the reaction of
phosphoric acid with a hydroxyl group of
sugar.E.g Glucose 6 phosphate, Glucose
1 phosphate.
• 2-Amino sugars are sugars whose
hydroxyl group is replaced by an amino or
acetylamino group.

46. Amino sugar.

47. • Examples are:
• A-Glucosamine which is product of
hydrolysis of chitin the major
polysaccharide of shells of insects and
crustaceans.
• B-Galactosamine is found in the
polysaccharide of cartalige,chondroitin
sulfate.

48. • 3-Sugar acids are produced by oxidation
of aldehyde carbon,hydroxyl carbon,or
both.
• Example:
• Ascorbic(Vitamin C) is a sugar acid.
• Glucuronic acid.

49. • 4- Deoxy sugars have a hydrogen atom in place of one
of their hydroxyl groups.
• E.g deoxyribose found DNA.
• 5-Sugar alcohols.
• Both aldoses and ketoses can be reduced at the
carbonyl carbon to the corresponding polyhydroxy
alcohols

50. • 1-Aldoses produce the corresponding
alcohols.
• D-Glucose produces D-Sorbitol.
• D-Mannose produces D-Mannitol.
• D-Galactose produces dulcitol.
• 2-Ketoses produce 2 alcohols.
• E.g. D-Fructose produces D-Mannitol and
D-Sorbitol.

52. COMPLEX CARBOHYDRATES.
• 1-Glycosaminoglycans consist of chains of
complex sugar made up of amino sugars
and uronic acid.
• They are made up of repeating units in
which D-Glucosamine or D-Galactosamine
or derivative of one of these sugars is
always present.
• E.g Heparin which act as anticoagulant.

53. • When is attached to protein molecule it is known
as Proteoglycan(Mucopolysaccharides).
• Examples:
• Chondroitin sulfate.
• Dermatan sulfate.
• Herparan sulfate.
• Keratan sulfate.
• Hyaluronic acid.

55. • Functions:
• Ground or packing substance. Associated with
the structural elements of tissues like
bones,elastin and collagen.
• Cushioning and Lubrication because they hold
large quantities of water and occupying space.
• This is helped by large negative charges on the
molecules which by repulsion keep the
carbohydrate chains apart.
•

58. • 2-Glycoproteins(Mucoproteins):
• They have different proteins attached by
covalent bond to polysaccharides chains.
• Protein-carbohydrate linkages.
• A-O- linked glycoproteins.
• These have sugars attached via the hydroxyl
group of a serine or threonine residue.
• B-N-linked glycoproteins.
• These have sugars attached via the amide NH2
group of an asparagine residue.

59. • All major types contain a common
pentasaccharide core which is linked to
asparagine via N-acetylglucosamine.
• The glycoprotein can be term as HIGH
MANNOSE, COMPLEX , or HYBRID
depending on the nature of the other
sugars attached to the core.

61. • Functions:
• A- Structural molecules( components of
cell walls and membranes).
• B-Lubricants(mucus).
• C-Cell attachment and recognition sites.
• D-Certain hormones(Human chorionic
gonadotropin,thyrotropin).
• E-Immunologic components-
immunoglobins,complement,interferon.

63. 3-The blood group Antigens:
• The blood group antigens are spicific
classes of oligosaccharides that may be
bound to proteins.
• There are more than 20 different blood
groups containing more than 150 different
antigens.
• The commonly studied blood group is the
ABO antigens.

65. • Blood types:
• A-Type O.
• Blood group O makes antibodies against
typeA and type B antigens .
• Receive blood only from blood group O.
• Donate blood to an individual with any
other blood type.
• It is known as UNIVERSAL DONOR.

66. • B-Type A.
• A person with blood group A makes
antibodies only to type B antigens and can
receive blood from either type O or type A
donors.
• Donates blood to either type A or type AB.

67. • C-TypeB.
• Makes antibodies against type A antigens
and can receive blood from either type O
or type B donors.
• Donates blood to either typeB or typeAB

68. • D-Type AB.
• Aperson with type AB blood group makes
no antibodies but receives blood from any
donor but donates blood only to other
type AB individuals.
• It is known as UNIVERSAL RECIPIENT.

71. Clinical correlations.
• The glycoside digitalis and its derivatives are
clinical significance because they inhibit the
Na+-K+ ATPase on the cell membranes.Such
drugs are used in the treatment of congestive
heart failure.
• Heparin is a glycosaminoglycan which is an
important anticoagulant( prevent coagulation of
blood) found in the granules of the mast cells.It
can be used during the treatment of myocardial
infarction( decrease of blood to the muscles of
the heart) as well as for the prevention of the
deep venous thrombosis during hospitalizations.

72. • The influenza virus infects cells by binding
its viral heamagglutinin to sialic acid on the
surface epithelial cells.

75. Assignment N0.2
• 1. Define and classify carbohydrates(give
examples and draw their sturctures)
• 2. Discuss about the 3 main
disaccharides( This should include its
formation, bonding, importance and
biomedical importances)
• 3. What are stereoisomers? Discuss about
the various types you know

76. • 4. Write an essay on
mucopolysaccharides and its biomedical
importance. Where necessary draw the
structures.
• 5. Discuss about glycosides and their
biomedical importances
• 6. Write an account on A. Polysaccharides
• B.Hyaluronic acid. C. Blood groups
• 7. Write an essay on the cell membrane