DNA polymerases are a group of enzymes that are used to make copies of DNA templates, essentially used in DNA replication mechanisms. These enzymes make new copies of DNA from existing templates and also function by repairing the synthesized DNA to prevent mutations. DNA polymerase catalyzes the formation of the phosphodiester bond which makes up the backbone of DNA molecules. It uses a magnesium ion in catalytic activity to balance the charge from the phosphate group.

1. DNAAND RNA
POLYMERASE
PREPARED BY; MISS RABIA KHAN BABER

2. AIMS AND OBJECTIVES OF PPT
DNA
POLYMERASE
ROLE AND
FUNCTIONS
EUKARYOTIC
DNA
POLYMERASE
DNA
POLYMERASE
FAMILY
DIFFERENCE
BETWEEN RNAAND
DNA POLYMERASE
DISCOVERY

3. DNA POLYMERASE
DNA polymerases are a group of enzymes that are
used to make copies of DNA templates, essentially
used in DNA replication mechanisms. These enzymes
make new copies of DNA from existing templates
and also function by repairing the synthesized DNA
to prevent mutations. DNA polymerase catalyzes the
formation of the phosphodiester bond which makes
up the backbone of DNA molecules. It uses a
magnesium ion in catalytic activity to balance the
charge from the phosphate group.

4. DISCOVERY
 DNA polymerase was first identified by Arthur
Kornberg in lysates of Escherichia coli, in 1956.
 The enzyme is found and used in the DNA replication
of both prokaryotic and eukaryotic cells.
 Several types of DNA polymerase enzymes have
been discovered with the first one to be discovered
named DNA polymerase I.

5. ROLE AND FUNCTION
 Each of these types plays a major role in replication
and DNA repair mechanisms.
 However, DNA polymerases are not used for
initiating the synthesis of new strands, but in the
extension of already existing DNA or RNA strands
which are paired with a template strand.
 DNA polymerase starts its mechanism after a short
RNA fragment is known as a primer is created and
paired with a template DNA strand.
 DNA polymerase acts by synthesizing the new DNA
strand by adding new nucleotides that match those of
the template, extending the 3′ end of the template
chain. Each nucleotide is linked with a
phosphodiester bond.

6. The DNA polymerase uses energy from the
hydrolysis of the bond that is between the three
phosphates attached to each nucleotides.
The addition of a nucleotide to a growing DNA
strand forms a phosphodiester bond between the
phosphate of the nucleotide to the growing chain
using the high-energy phosphate bond of
hydrolysis, releasing two distal phosphates known
as pyrophosphate.
DNA polymerases are very accurate in their
mechanism with minimal errors of less than one
error for every 106 nucleotides.

7.  Some types of DNA polymerase have the ability to
proofread and remove unmatched bases of nucleotides and
correct them.
 They also correct post-replication mismatches by
monitoring and repairing the errors, by distinguishing
mismatches of the new strand from the template strand
sequences.
 The eukaryotic cell contains five DNA polymerase α, β, γ,
δ, and ε. Polymerase γ is found in the cell mitochondria
and it actively replicates the mitochondrial DNA, while
polymerase α, β, δ are found in the cell nucleus hence are
involved in the nuclear DNA replication.
 Polymerase α and δ are majorly applied and active in
diving cells hence involved in replication while
polymerase β is active in both diving and nondividing
cells hence it is involved in the repair of DNA damage.

8. EUKARYOTIC DNA POLYMERASE
• DNA Polymerases play a key role in the synthesis of
DNA. These polymerases are multi-subunit complexes
that function very uniquely. It requires different
components to work together to function efficiently.
Polymerases act upon single-stranded strands to
synthesize a strand that is complementary. In eukaryotic
cells, there are 5 families of DNA polymerase. These
can encode into different enzymes. Critical for DNA
replication are three DNA polymerases: Polymerase α-
primase, Polymerase δ, and Polymerase ε. These three
polymerases function at the replication fork of the DNA
strands. The DNA strands are by helicase. It is
Polymerase α- primase that initiates replication on the
leading and lagging strand. It is here that the RNA
primers (about 10 nucleotides) are laid down.

9. DNA POLYMERASE FAMILY
FAMILY A Includes DNA polymerase I
FAMILY B Includes all eukartyotic DNA
polymerase s involved in
chromosomal replication
FAMILY X
Includes all enzyme
responsible for the repair or
specialized type of DNA
replication.
FAMILY Y
RT FAMILY

10. DNA POLYMERASE TYPES-
FAMILY A
Polymerase γ
Polymerase γ is a Type A polymerase, whose
main function is to replicate and repair
mitochondrial DNA.
It also functions by proofreading 3′ to 5′
exonuclease activity.
Mutations on Poly γ significantly affect the
mitochondrial DNA causing autosomal
mitochondrial disorders.

11. DNA POLYMERASE TYPES-
FAMILY B
Polymerase α, Polymerase δ, and Polymerase ε
 These are the type B Polymerase enzymes and they are the
main polymerases applied in DNA replication.
 Pol α works by binding to the primase enzyme, forming a
complex, where they both play a role in initiating
replication. Primase enzyme creates and places a short RNA
primer which allows Pol α to start the replication process.
 Pol δ starts the synthesis of the lagging strand from Pol α,
while Pol ε is believed to synthesize the leading strand
during replication.
 Studies indicate that Pol δ replicates both the lagging and
leading strand.
 Pol δ and ε also have a 3′ to 5′ exonuclease activity.

12. DNA POLYMERASE TYPES-
FAMILY X
Polymerase β, Polymerase μ, and Polymerase λ
 These are type 3 or Family X of polymerase enzymes.
 Pol β has a short-patch base excision repair
mechanism where it repairs alkylated or oxidized
bases.
 Pol λ and Pol μ are important for rejoining DNA
double-strand breaks due to hydrogen peroxide and
ionizing radiation, respectively.

13. DNA POLYMERASE TYPES-
FAMILY Y
 Polymerases η
 Polymerase η functions by accurately ensuring the translesion
synthesis of DNA damages that is caused by ultraviolet
radiation.

14. S.No# CHARACTERISTICS DNA POLYMERASE RNA POLYMERASE
1. DEFINITION It is an enzyme that synthesizes the DNA
It is an enzyme synthesizes
the RNA
2. MECHANISM
DNA polymerase’s mechanism is during replication
whereby it synthesizes new DNA strands
RNA polymerase functions
during transcription, which
is the synthesis of RNA
3. STRANDS It synthesizes a double-stranded DNA molecule
It synthesizes a single-
stranded RNA molecule
4.
PRESENCE OR
ABSENCE OF
PRIMER
Its replication mechanism is initiated by a short-
RNA primer
It does not need a primer to
initiate transcription
5.
NUCLEOTIDE
INSERTION
It inserts nucleotides after finding the free 3’ OH
end by the assistance of the primer-synthesizer,
primase enzyme
It adds nucleotides directly.
6. BASE PAIRS
It adds Adenine-Thymine and Guanine-Cytosine
base pairs
It adds Adenine-Uracil and
Guanine-Cytosine base
pairs

15. CONT..
7.
FUNCTIONALITY
It has polymerization and proofreading
activity
RNA polymerase only has a polymerization
activity.
8. POLYMERIZATION
RATE
The rate of polymerization by DNA
polymerase is about 1000 nucleotides
per second in prokaryotes
The rate of RNA polymerase is 40 to 80
nucleotides per second.
9.
EFFICIENCY
DNA polymerase enzyme is faster,
efficient, and more accurate
considering its proofreading activity.
RNA polymerase is slower, inefficient, and
inaccurate.
10.
TERMINATION
The DNA synthesis continues until the
end when the strand ends, that is when
polymerization stops, thus the entire
chromosomal DNA is synthesized.
The polymerization is terminated when
RNA polymerase finds the stop codon or
termination codon on the nucleic acid
strand.

16. THANKYOU !!