This presentation talks about the chemical composition of DNA. DNA is a double helical structure made from purines and pyrimidine. Happy Reading!

1. Chemical
composition of DNA
MANSI
BSC Biotech Hons.

2. What all we will study is-
• History of DNA
• What is DNA?
• DNA structure
• DNA components

3. HISTORY
• DNA was discovered in 1869 by Swiss researcher Friedrich
Miescher, who was originally trying to study the composition
of lymphoid cells (white blood cells). Instead, he isolated a
new molecule he called nuclein (DNA with associated
proteins) from a cell nucleus.

4. WHAT IS DNA?
• •DNA [deoxyribonucleic acid] is a polymer of a
deoxyribonucleotide.
• • DNA or deoxyribonucleic acid is a long molecule
that contains our unique genetic code. Like a recipe
book, it holds the instructions for making all the
proteins in our bodies.
• DNA contain four basic building blocks or ‘bases’:
• adenine(A), cytosine (C), guanine (G) and thymine
(T).

5. • Each chain is formed by many
nucleotides{nucleotides= nitrogenous base +
pentose sugar + phosphate group} linked
together through phosphodiester bond.
• example- adenosine, cytidine etc.
• Nitrogenous bases are of four types-
Adenine, guanine, thymine, cytosine.
• Sugar present in DNA is deoxyribose sugar.

7. • Complementary bases pair with each other through a
hydrogen bond.
• Purines always pair with their corresponding
pyrimidine's. adenine pairs with thymine through 2- H
bonds while guanine pairs with cytosine through 3-H
bonds.
• In course of formation of a polynucleotide chain, a
phosphate group remains free at 5' end of a ribose sugar
and 1-OH group remains free at 3' end ribose.

9. THANK YOU