Biomolecules are organic compounds that serve as the building blocks of living organisms. The four most abundant elements in the human body are carbon, hydrogen, oxygen and nitrogen. Biomolecules are typically carbon-based and have specific three-dimensional shapes defined by bonds between carbon atoms. Functional groups on biomolecules, such as hydroxyl, amino and carboxyl groups, determine their chemical properties. Carbohydrates are an important class of biomolecules that serve as energy stores. They are made of carbon, hydrogen and oxygen and can exist as monosaccharides, disaccharides or polysaccharides.

1. INTRODUCTION
BIOMOLECULES

2. What is a Biomolecule?
⮚ Organic compound (CHONSP) present as
essential component of living organisms.
⮚ Organic compounds are molecules containing
covalently bonded carbon backbones.
⮚ Serve as building blocks of cells.
⮚ Participate in dynamic functions.

3. Biomolecules: The Molecules of Life
⚫ Element Human body (% age)
❖ C 9.5%
❖ H 63%
❖ O 25.5%
❖ N 1.4%
❖ P 0.22%
⚫ values are given as %age of total number of atoms
present.
H, O, C and N make up 99% of atoms in the
human body

4. IMPORTANT FEATURES OF
BIOMOLECULES
⮚Most biomolecules are carbon
compounds.
⮚Organic molecules have specific shapes
and dimensions.
⮚Functional groups of organic molecules
determine their chemical properties
(hydroxyl,amino,carbonyl and carboxyl
group)
⮚Most of the biomolecules are
polyfunctional.
⮚ Biomolecules are assymetric and have
3-D structures.

5. Properties of carbon
compounds
⚫Their ability to form covalent bonds by
electron-pair sharing.
⚫Significant ability to form C-C single
bonds( very stable)
⚫Capacity to form C-C,C=C.
⚫Covalently linked carbon atoms can be
joined to form
⮚Linear chain
⮚Branched chain
⮚Cyclic

6. Organic molecules have specific shapes and
dimensions.
⮚ Tetrahedral arrangement of C-atoms.
⮚ An angle of 109.5deg is btw.any 2-C atoms.
⮚ Organic compounds have 3-D structure.
⮚ In organic compounds there is a complete
freedom of rotation around C-C unless some
large groups interfere.
⮚ Bond lenth: C-C (0.154nm)
C= C (0.134 nm)

7. Functional groups determine chemical
property
⮚ Alcohol OH group
⮚ Amines NH2 group
⮚ Ketone C=O group
⮚ Aldehyde CHO group
⮚ Thiol S-H group
⮚ Ester R-COO group.
⮚
⚫ Functional groups are chemically more
reactive than saturated hydrocarbon
backbones.

8. DEFINITIONS
⮚ Chiral /Assymetric compound.
⮚ Enantiomers.
⮚ Configuration
⮚ Conformation.
⮚ Steriospecificity.
⮚ Racemic Mixture
⮚ Epimers
⮚ Furan/ Furanose
⮚ Pyran/ Pyranose
⮚ Hemiacetal/ Hemiketal
⮚ Anomers

9. ❖ Chiral Compound :
⮚ A compound that contains an asymmetric
centre and is capable of occurring in 2 non
superimposable mirror images.
⮚ A carbon atom that is covalently bonded to
four different groups and may occupy 2
different tetrahedral configurations is called
an assymetric carbon atom.
Tetrahedral
carbon atom
bonded to four
different groups

10. Enantiomers
✔ An optically active compound that rotates
the plane of polarized light either to left or
to right.
✔ Isomers that are non superimposable
mirror images of each other. Also known
as optical isomers or sterioisomers.
Ex: D-and L-glyceraldehde.

12. ❖ Conformation:
⮚ A spatial arrangement of substituent groups
that are free to assume different positions in
space without breaking any bonds, because of
freedom of bond rotation.
❖ Configuration:
⮚ A spatial arrangement of organic molecule
that is conferred by the presence of either
i. Double bonds about which there is no
freedom of rotation.
ii. Chiral centres around which subsequent
groups are arranged in specific sequence.
❖ Configurational isomers cannot be
interconverted without breaking one or more
covalent bonds.

13. ⚫Furan: is a heterocyclic organic
compound.
⚫Furanose : is a simple sugar that
contains a five membered furan-based
ring structure. Furanose ring consists of
4-C and 1-O atom.
⚫Pyran: is a six membered heterocyclic
ring consisting of 5 –C and 1-O atom
and contain 2 double bonds.
⚫Haworth perspective Formulas: used to
form ring form of monosaccharides.

14. ❖Racemic Mixture:
⮚ A mixture containing equal amounts of
each of the two isomers of a chiral
molecule (assymetric molecule) .
Ex: (dl-mixture)
Hemiacetal/ Hemiketal: The general
reaction of a carbonyl group ( aldehyde or
ketone) with an alcohol forms
hemiacetal//hemiketal.

15. Carbohydrates Contain the Elements:
■Carbon
■Hydrogen
■Oxygen
General formula : (C H2O)n
C : H :O 1: 2:1
n represents the number of times the CH2O
unite is repeated.
“ Carbohydrates are Polyhdroxy aldehydes or
ketones”
Carbohydrates

16. CLASSES OF CARBOHYDRATES
⚫ Monosaccharides (Monomers)
✔ Simple sugars
✔ Single polyhdroxy aldehyde or ketone.
Ex: D-glucose.
⚫ Oligosaccharides ( Oligos: few)
✔ Short chains of monosaccharide units joined by
covalent bonds.
Ex: Disaccharides ( sucrose)
⚫ Polysaccharides (Polymers)
✔ Consist of long chains having hundreds and
thousands of monosaccharide units
Ex: Starch and glycogen.

18. ⮚Used to represent 3-dimensional
structure on paper.
⮚ Horizontal bonds project out of
a plane of paper towards reader.
⮚ Vertical bonds project behind
the plane of paper away from the
reader.

19. Aldoses

20. Ketoses

21. Glucose
■The chemical formula
for glucose is C6H12O6.
■It is a six sided ring.
■The structure on the
left is a simplified
structure of glucose
The Most Important Monosaccharide is Glucose.

22. Epimers :
❑ When 2 sugars differ only in the configuration around
one carbon atom they are called epimers.
Ex: D- Glucose and D- Mannose ( C2 –epimers)
D-Glucose and D-Galactose (C4-epimers)
❑ Epimers are special class of diasteromers
Diastereomers are isomers with > 1 chiral center.
– Pairs of isomers that have opposite configurations at
one or more of the chiral centers but that are not mirror
images of each other.

23. ⚫ Anomers: Isomeric forms that differ from each other in
configuartion about one hemiacetal carbon atom are
called anomers.
⚫ Hemiacetal or carbonyl carbon is known as anomeric
carbon.
Ex: α –D- glucopyranose and β- D glucopyranose.

24. DISACCHARIDES
⚫ Disaccharide is a sugar composed of two
monosaccharides.
⚫ Disaccharides are most commonly occurring
oligosaccharides in nature and on hydrolysis yeild
monosaccharides.
⚫ Ex: Maltose, Lactose and sucrose.
Disacchari
de
Unit 1 Unit 2 Bond
Sucrose Glucose Fructose α ( 1-2)
Lactose Galactose Glucose β (1-4)
Maltose Glucose Glucose α ( 1-4)
Trehalose Glucose Glucose α (1-1)

25. ⮚ Bond between sugar and another
molecule (alcohol,purine,pyrimidine
or sugar) through an oxygen or
nitrogen atom.
⮚ Two monosaccharides bonded via a
condensation reaction which leads to
removal of water.
⮚O-glycosidic
⮚N-glycosidic
Glycosidic Bond

26. Glycosidic Bond
⧫Glycosidic bond.

27. ■ The structural
formula for
Maltose.
■The structural
formula for
Lactose.
Structural formula

28. Hydrolysis
⚫This is the breaking down of a
glycosidic bond.
⚫Instead of water been taken away
water is added.
⚫Lysis means splitting.

29. POLYSACCHARIDES
⮚ Also known as glycans.
⮚ Polymers of hundreds or thousands of
monosaccharide's units held together by
glycosidic linkage.
⮚ Homo/Heteropolysaccharides
⮚ Structural polysaccharides ( Cellulose and
Chitin)
⮚ Storage Polysaccharides. ( Starch &
Glycogen)