Molecular Basis of Life:
DNA: Composition, Structure, and Replication
, index
1. What is DNA
2. Its Composition
3. Structure
4. Discovery
5. Requirements for a Genetic Material; and why DNA emerged in nature
as the genetic material
6. The first Genetic Material
7. Semi-Conservative DNA Replication
8. Past Year Question
,Over the years after Mendel, the nature of genetic material was investigated , resulting in the realization
that DNA is the genetic material in most organisms (in some viruses like TMV, Retroviruses, etc. RNA has
that role).DNA and RNA are to types of nucleic acids found in living systems; nucleic acids are polymers of
nucleotides. Let us move further by firstly understanding the structure of DNA; in subsequent sections we
will understand that why it is the most abundant genetic material, and what its relationship with RNA is.
What It is a long polymer sequence of deoxyribonucleotides
is Its length is usually defined- as number of nucleotides (or a pair of
nucleotides known as base pairs) present in it . This also is the
.
DNA characteristic
Organism of anGenetic
F 174
organism.
Material
ssDNA, Circular
N.Nucleotides (bp)
5386 Bases
Bacteriophage
l Phage dsDNA ,Linear 48,052
Escherichia coli dsDNA, Circular 4.6×106
Human dsDNA, Linear 3.3×109
, Structure In order to understand the structure of DNA we’ll
have to know the structure of its basic unit, k/a -
Nucleotide
• It comprises of a pentose sugar
Phosp
hate ( RNA:Ribose,DNA:Deoxyribose)to it attach a
Group phosphate group, and a nitrogenous base.
Pentose • Nitrogenous bases
Sugar
(RNA- Heterocycli Heterocycli
Ribose Nucleoti Purines c
Pyrimidin
es c
DNA- de Nitrogenous 9 6
Deoxyribo Base membered membered
se) double ring single ring
N at N at
positions positions 1,
1,3,7,9 Cytosine
and 3
Adenine (C)
(A) Thymine (T)
Guanine (DNA)
(G) Uracil (U)
(RNA)
DNA: Composition, Structure, and Replication
, index
1. What is DNA
2. Its Composition
3. Structure
4. Discovery
5. Requirements for a Genetic Material; and why DNA emerged in nature
as the genetic material
6. The first Genetic Material
7. Semi-Conservative DNA Replication
8. Past Year Question
,Over the years after Mendel, the nature of genetic material was investigated , resulting in the realization
that DNA is the genetic material in most organisms (in some viruses like TMV, Retroviruses, etc. RNA has
that role).DNA and RNA are to types of nucleic acids found in living systems; nucleic acids are polymers of
nucleotides. Let us move further by firstly understanding the structure of DNA; in subsequent sections we
will understand that why it is the most abundant genetic material, and what its relationship with RNA is.
What It is a long polymer sequence of deoxyribonucleotides
is Its length is usually defined- as number of nucleotides (or a pair of
nucleotides known as base pairs) present in it . This also is the
.
DNA characteristic
Organism of anGenetic
F 174
organism.
Material
ssDNA, Circular
N.Nucleotides (bp)
5386 Bases
Bacteriophage
l Phage dsDNA ,Linear 48,052
Escherichia coli dsDNA, Circular 4.6×106
Human dsDNA, Linear 3.3×109
, Structure In order to understand the structure of DNA we’ll
have to know the structure of its basic unit, k/a -
Nucleotide
• It comprises of a pentose sugar
Phosp
hate ( RNA:Ribose,DNA:Deoxyribose)to it attach a
Group phosphate group, and a nitrogenous base.
Pentose • Nitrogenous bases
Sugar
(RNA- Heterocycli Heterocycli
Ribose Nucleoti Purines c
Pyrimidin
es c
DNA- de Nitrogenous 9 6
Deoxyribo Base membered membered
se) double ring single ring
N at N at
positions positions 1,
1,3,7,9 Cytosine
and 3
Adenine (C)
(A) Thymine (T)
Guanine (DNA)
(G) Uracil (U)
(RNA)
