DNA sructure describing all thecomponents of dna.pdf

Dna structure

1. DNA: The Blueprint of Life
Unraveling the Structure of Our Genetic Code
Abhishek Pandey
M.Sc Microbiology
3rd Sem

2. What is DNA? The Molecule of Heredity
●DNA stands for Deoxyribonucleic
Acid.
●It is the biological instruction manual
that makes every species unique.
●Carries the genetic information for
the development, functioning, growth,
and reproduction of all known
organisms and many viruses.
●In eukaryotes (like humans, animals,
and plants), DNA is located in the
cell's nucleus.
●In prokaryotes (like bacteria), it is
found in the cytoplasm in a region
called the nucleoid.

3. The Building Blocks: Nucleotides
DNA is a long molecule made of repeating chemical units
called nucleotides. Each nucleotide consists of three parts:
1.A Phosphate Group
2.A Deoxyribose Sugar
(a 5-carbon sugar)
3.A Nitrogenous Base
These three components form the
fundamental unit that builds the DNA
chain.

4. The Four Nitrogenous Bases
There are four types of nitrogenous
bases in DNA, divided into two classes:
●Purines (double-ring structure)
○Adenine (A)
○Guanine (G)
●Pyrimidines (single-ring structure)
○Cytosine (C)
○Thymine (T)

5. The Sugar-Phosphate Spine
●To form a strand of DNA,
nucleotides are linked into a chain.
●The phosphate group of one
nucleotide covalently bonds to the
sugar of the next.
●This creates a strong, repeating
pattern known as the
sugar-phosphate backbone.
●This backbone provides structural
support and runs along the outside
of the helix, while the bases face
inward.

6. The Double Helix & Base Pairing
●DNA is composed of two strands that
twist around each other to form a
right-handed spiral, known as a double
helix.
●The two strands are held together by
hydrogen bonds between the nitrogenous
bases.
●Complementary Base Pairing Rule:
○Adenine (A) always pairs with Thymine
(T) with two hydrogen bonds.
○Guanine (G) always pairs with Cytosine
(C) with three hydrogen bonds.

7. Key Features of the Double Helix
●Antiparallel Strands: The two
DNA strands run in opposite
directions. One strand runs from
the 5' (five-prime) end to the 3'
(three-prime) end, and the other
runs from 3' to 5'.
●Major and Minor Grooves: The
twisting of the strands creates
uneven gaps. These "grooves" act
as important binding sites for
proteins that read the DNA
sequence.
Anti Parallel Strands

8. Summary: The Importance of DNA's Structure
DNA's structure is a double helix with an antiparallel sugar-phosphate backbone.

The two strands are joined by specific A-T and G-C base pairs.
This elegant and stable structure is
crucial for its function:
Storing Information: The sequence of
bases stores a massive amount of
genetic data.
Accurate Replication: The base pairing
rule allows the molecule to be copied
with incredible precision, ensuring
genetic information is passed on
correctly.