hafiz m waseem university of education lahore msc zoology basically iam from mailsi vehari studied in multan then in lahore

1. Carbohydrates
Classification of Carbohydrates (On the Basis of Size)
Monosaccharides
General Biochemistry
hafiz m waseem
ue lahore

3. Biochemistry
• Biochemistry can be defined as the science concerned with the chemical basis of life.
• The cell is the structural and functional unit of living organisms. Thus biochemistry can also
be defined as the science concerned with the chemical constituents of living cells and with
the reactions and processes they undergo (Harper).
• Biochemistry is the study of the chemistry of life processes (Stryer).

4. Carbohydrates
Carbohydrates are polyhydroxy aldehydes or ketones, or substances that
yield such compounds on hydrolysis.
Carbohydrates are the most abundant biomolecules on earth. Many
carbohydrates have C, H, and O, but some also contain nitrogen, phosphorus or
sulphur. As they contain H and O in the same ratio as in water, they are also called
as the Carbon Hydrates or Hydrates of Carbon.
C O C O
H
C O
C
Cabonyl Group Aldehyde Group Ketone Group
C

5. Classification of Carbohydrates (On the Basis of Size)
Carbohydrates are divided into three major size groups or classes;
• Monosaccharides
• Oligosaccharides
• Polysaccharides (the word "saccharide" is derived from the Greek sakcharon,
meaning "sugar")
Monosaccharides
Monosaccharides are simple sugars and consist of a single polyhydroxy
aldehyde or ketone unit. They cannot be hydrolyzed into simpler carbohydrates.
The most abundant monosaccharide in nature is the six-carbon sugar D-glucose,
sometimes referred to as dextrose.

6. Empirical Formula
Many monosaccharides have the empirical formula as (CH2O)n, where n is
not less than 3. All common monosaccharides and disaccharides have the names
ending with the suffix-ose.
Classification of Monosaccharides on the Basis of C-Atoms:
Most of the monosaccharides have carbon atoms from 3 to 7and are named
accordingly;
• 3C – Trioses
• 4C – Tetroses
• 5C – Pentoses
• 6C – Hexoses
• 7C - Heptoses

7. Classification of Monosaccharides on the Basis of Functional Groups:
Monosaccharides with aldehyde group are called as Aldoses whereas with
ketone group are called as Ketoses. If the carbonyl group is at the end of carbon
chain, it is an aldehyde group, and the monosaccharide is an aldose sugar. If the
carbonyl group is at any other position, it is a ketone group, and the
monosaccharide is a ketose sugar.
The simplest monosaccharides are the two 3-carbon trioses;
• Glyceraldehyde, an aldotriose
• Dihydroxyacetone, a ketotriose
C
C OH
H
C
C
C
H
C
D-Glyceraldehyde,
an aldotriose
Dihydroxyacetone
a ketotriose
H OH
H
H OH
H
H
H
O
H
OH

8. The most common hexoses in nature are;
• D-Glucose, an aldohexose
• D-fructose, a ketohexose
C
O
H
C OH
C
H
HO
C
C
C
HO
H
C
H
H OH
O
H
C
H
OH
C
H
OH
CH2OH
H
D-Glucose, an aldohexose
OH
H
C OH
H
CH2OH
D-Fructose, a ketohexose

9. The most common pentoses are;
• D-Ribose, an aldopentose
• 2-Deoxy-D-Ribose, an aldopentose
These sugars are components of nucleotides and nucleic acids.
C
C
C
C
CH2OH
OH
OH
OH
H
H
H
O
H
D-Ribose, an aldopentose
C
H O
C
C
C
CH2OH
H
H
H
H
OH
OH
2-Deoxy-D-ribose, an aldopentose

10. Characteristics of Monosaccharides
Stereochemistry
Stereochemistry deals with the study of the arrangement of atoms of a
molecule in three- dimensional space.
Stereoisomers
Compounds that have the same composition and the same chemical bonds
but different stereochemistry, i.e., different configuration, are called stereoisomers.
Configuration
The fixed spatial (in space) arrangement of atoms in a molecule is called as
configuration.
Stereo Specificity in Biomolecules
Interactions between biomolecules are invariably (extremely) stereospecific,
requiring specific stereochemistry in the interacting molecules.

11. Asymmetric Carbon or Chiral Center
A carbon atom with four different substituents is called Asymmetric Carbon
or Chiral Center (Greek chiros, "hand"; some stereoisomers are related structurally
as the right hand is to the left).
A molecule with only one chiral carbon can have two stereoisomers.
C
A
B
D
E

12. General Formula
A molecule having n numbers of chiral carbons will have 2n numbers of stereoisomers.
CHO
C OH
H
CH2OH
C
CHO
H
HO
CH2OH
D-Glyceraldehyde L-Glyceraldehyde
Enantiomers
If the stereoisomers are mirror images of each other, they are called enantiomers.
Diastereomers
Stereoisomers that are not mirror images of each other, they are called diastereomers.

13. Louis Pasteur first observed that enantiomers have nearly
identical chemical properties but differ in a characteristic property,
their interaction with plane polarized light. In separate solutions, two
enantiomers rotate the plane of polarized light in opposite directions,
but an equimolar solution of the two enantiomers ( a racemic mixture)
shows no optical rotation.
Compounds without chiral centers do not rotate the plane
polarized light.