Definition What constitute a chemical bond? Types of bond 1. Strong bond Covalent bond Glycosidic bond Peptide bond Disulfide bond 2. Weak bond Hydrogen bond Van der waals bond Hydrophobic bond Ionic bond Conclusion References

1. By
KAUSHAL KUMAR SAHU
Assistant Professor (Ad Hoc)
Department of Biotechnology
Govt. Digvijay Autonomous P. G. College
Raj-Nandgaon ( C. G. )

2. Synopsis
Definition
What constitute a chemical bond?
Types of bond
1. Strong bond
Covalent bond
 Glycosidic bond
 Peptide bond
 Disulfide bond
2. Weak bond
 Hydrogen bond
 Van der waals bond
 Hydrophobic bond
 Ionic bond
Conclusion
References

3. Definition
 A chemical bond is an attraction
between atoms that allows the
formation of chemical substances that
contain two or more atoms

4. What constituent
chemical bond?
 A bond is formed when electrons from
two atoms interact with each other
and their atoms become joined.

5. Types of bond
 Strong bond
covalent bond
covalent bond in biomolecules are
• Glycosidic bond
• Peptide bond
• disulphide bond
• PHOSPHODIESTER BOND
 Weak bond
• Hydrogen bonding
• Van der waals bonding
• Hydrophobic bond
• Ionic bond

6. Strong bond

7. Covalent Bond
 Between nonmetallic elements of
similar electronegativity.
 Formed by sharing electron pairs
 Examples; O2, CO2, C2H6, H2O,

9. 2. Covalent bonds- Two atoms share one or more pairs of outer-shell
electrons.
Oxygen Atom Oxygen Atom
Oxygen Molecule (O2)

10. Glycosidic bond
A glycosidic bond is formed between
the hemiacetal group of a saccharide (or a
molecule derived from a saccharide) and
the hydroxyl group of some organic
compound such as an alcohol.
•The bond is formed
between monosaccharide
to form disaccharides
•Also seen in DNA where
nitrogenous bases form N-
glycosidic bond with sugar
molecule
Glycosidic bond in carbohydrates
Glycosidic bond in DNA

11. Peptide bond
 Amino acid are covalently linked by amide
bonds (–CO-NH-) (Peptide Bonds)
 The resulting molecules are called Peptides &
Proteins
 Polypeptides and proteins are chains
of amino acids held together by peptide
bonds

12. Disulfide bond
 A disulfide bond is a covalent bond, usually derived by the
coupling of two thiol groups. The linkage is also called an SS-
bond or disulfide bridge. The overall connectivity is
therefore R-S-S-R
 formed between the thiol groups of cysteine residues.

13. Phosphodiester bond
 A phosphodiester bond is a group of
strong covalent bonds between a phosphate
group and two 5-carbon
ring carbohydrates (pentoses) over
two ester bonds.
 In DNA and RNA, the phosphodiester bond is the
linkage between the 3' carbon atom of one sugar
molecule and the 5' carbon atom of another; the
sugar molecules being deoxyribose in DNA
and ribose in RNA.

14. Phosphodiester
bond

15. Weak bond

16. Hydrogen bond
 A hydrogen bond is the electromagnetic attractive
interaction of a hydrogen atom and
an electronegative atom, such as
nitrogen, oxygen or fluorine, that comes from
another molecule or chemical group
 Intramolecular hydrogen bonding is partly
responsible for the secondary, tertiary,
and quaternary structures of proteins and nucleic
acids

17. Hydrogen bonding in DNA
Hydrogen bonding in proteins

18. Van der waals bonds
 Van der waals force is the sum of the attractive or
repulsive forces between molecules (or between
parts of the same molecule) other than those due
to covalent bonds, the hydrogen bonds, or
the electrostatic interaction of ions with one
another or with neutral molecules

19. Hydrophobic bond
 Meaning “Water fearing”
 The hydrophobic effect is the observed tendency
of nonpolar substances to aggregate in aqueous
solution and exclude water molecules

21. IONIC BOND
Bond formed between
two ions by the
transfer of electrons

22. Formation of Ions from Metals
 Ionic compounds result when metals react
with nonmetals
 Metals lose electrons to match the number
of valence electrons of their nearest noble
gas
 Positive ions form when the number of
electrons are less than the number of
protons
Group 1 metals  ion 1+
Group 2 metals  ion 2+

23. Ionic Bond
 Between atoms of metals and nonmetals
with very different electronegativity
 Bond formed by transfer of electrons
 Examples; NaCl, CaCl2, K2O
 Ionic interactions- Some amino acids have
charged R groups, which attract oppositely
charged R groups and repel those with like
charges.

25. Ionic Bonds: One Big Greedy Thief Dog!

26. 1). Ionic bond – electron from Na is transferred to Cl,
this causes a charge imbalance in each atom. The Na
becomes (Na+) and the Cl becomes (Cl-), charged
particles or ions.

27. Conclusion
 Believe it or not, the chemical properties of almost
any substance or material in the world depend
upon the chemical bonds that make it up.
 If it weren't for chemical bonds, every material in
the world would have to be one of the 118
elements in the Periodic Table. Instead, atoms from
these elements bond together to create chemical
compounds.
 There are chemical bonds between the atoms in
our bodies (especially the elements carbon,
hydrogen, and oxygen), the atoms in the air, and
the atoms in most plants and synthetic materials.
 In fact, chemical bonds are everywhere, and when
two elements bond together, their properties often
change completely.

28. References
 Nelson and cox – Principle of
biochemistry. 5th edition
 Voet D, Voet JG and Pratt CW –
Fundamentals of biochemistry. 2nd
edition
 www.tokresource.org
 www.labspace.open.ac.uk