Overview of carbohydrates with emphasis on monosaccharides including their properties.

1. CARBOHYDRATES
Submitted by-
Saniya Khan

2. INTRODUCTION
• Carbohydrates or saccharides are polyhydroxy
aldehydes or ketones or their derivatives or
substances that yield such products on hydrolysis.
• These are organic compounds made up of carbon,
hydrogen and oxygen.
• Usually hydrogen and oxygen atom are in the ratio
2:1.

3. FUNCTIONS OF CARBOHYDRATES
• Providing energy and regulation of blood glucose.
• Sparing the use of proteins for energy.
• Breakdown of fatty acids and preventing ketosis.
• Biological recognition processes.
• Flavor and Sweeteners.
• Dietary fiber.

4. CLASSIFICATION

5. MONOSACCHARIDES
• These are simple sugars, or the compounds which
possess a free aldehyde (-CHO) or ketone (-C=O) group
and two or more hydroxyl (-OH) groups. They can’t be
hydrolyzed further into simpler units.
• General formula is CnH2nOn.
• They contain a single carbon chain and are classified on
the basis of number of carbon atoms present, and as
ketoses or aldoses depending upon their functional
groups.

6. CLASSIFICATION OF MONOSACCHARIDES

7. • Glucose, fructose and galactose are of importance in
human nutrition. All having formula C6H12O6 .
• Glucose (blood sugar) is the primary carbohydrate
used by the body. It is also known as dextrose.
• Fructose (fruit sugar) is the sweetest of all the sugars.
It is also known as levulose.
• Galactose is found in combination with glucose in
milk.

8. PROPERTIES OF MONOSACCHARIDES
• Isomerism- compounds having same molecular
formula but different structure/orientation. This is due
to presence of asymmetric or chiral carbon atom.
1) D & L isomers- when –OH group around C atom
adjacent to terminal primary alcohol C is on the right
then it is designated as D-series and when on left then
L-series.
2) Sterioisomers- same molecular formula and
structure but differ in spatial configuration.
a) Cis-trans isomers- contains double bonds.

9. b) Optical Isomers or enantiomers- when a beam of plane
polarized light is passed through a solution exhibiting
optical activity, it will be rotated to right (dextro rotatory
or +) or left (laevo rotatory or -) in accordance to the type
of mixture.
3) α and β anomers- change in the position of H and OH at
C1 forms anomers.
4) Epimers- Isomers formed as a result of interchange of
OH and H at C2, C3 & C4.
5) Aldose and Ketose- monosaccharide containing ketone
group (fructose) are ketose sugar and aldehyde group
(glucose) are aldose sugar.

10. 6) Furanose & Pyranose- cyclic sugars containing 5
membered ring are furanoses (fructose) and 6
membered ring are pyranoses (glucose).
Enantiomers

11. Trans-Cis isomers
Epimers

12. • Oxidation- in the presence
of oxidizing agent,
terminal aldehyde or
ketone or terminal alcohol
or both the groups maybe
oxidized.
• Reduction- in the presence
of reducing agent ketone
and aldehyde are reduced
to corresponding alcohol.

13. • Reducing Power- Sugars having free aldehyde or ketone
group have an ability to reduce cupric ions to cuprous
ions and are known as reducing sugars. Reducing nature
is more prominent in alkaline solution than acidic
solution.
• Dehydration- when treated with conc. Sulphuric acid,
sugars undergo dehydration with removal of 3 molecules
of water leading to formation of hydroxy methyl furfural
(in case of hexoses) or furfural (in case of pentoses).
• Osazone formation- ketose or aldose sugar reacts with
phenyl hydrazine to give osazone which have
characteristic shape and can be needle (glucose,
fructose), sunflower (mannose) or puff (lactose) shaped.

14. • Ester formation- alcoholic group if carbohydrates may be
esterified both enymatically and non-enzymatically.
• Tautomerization or Enolizaton- process of shifting of H atom
from one C atom to another C atom leads to production of
enediols and this process is known as tautomerization.