This document summarizes DNA and RNA polymerases. It discusses: - The three main types of prokaryotic DNA polymerases (DNA polymerase I, II, and III), what they are responsible for, and how they work. - The main eukaryotic DNA polymerases (DNA polymerase α, β, γ, δ, and ε), what they are responsible for, and how they work. - RNA polymerase, the main types in bacteria and eukaryotes, their subunits, and how they work to transcribe DNA into RNA through the process of transcription.

1. S 1
Presented By:
Mohsin Shad (2013-Bc-005)
Asmat Shahzad (2013-Bc-026)
Muhammad Zulqarnain (2013-Bc-027)
Hamza Zafar (2013-Bc-032)
Presented To :
Miss Huma Mujahad

2. DNA AND RNA POLYMERASES 2

3. DNA Polymerases
• The enzymes that create DNA molecules by assembling
nucleotides
• These enzymes are essential to DNA replication
• They usually work in pairs to create two
identical DNA strands from a single original DNA molecule
• There are three main types of prokaryotic DNA polymerases
• DNA polymerases I
• DNA polymerases II
• DNA polymerases III
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4. DNA Polymerases I
• DNA Polymerases I was firstly discovered in 1958 by
Arthur Kornberg who received Noble Prize in
Physiology and Medicine in 1959
• DNA Polymerases I is mainly responsible for:
• Proofreading of DNA strand
• Repairing of damage DNA
• Filling the gap between the okazaki fragments
• Removal of RNA primer
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5. DNA Polymerases II
• DNA Polymerases II was identified later during
the experiment on mutant E.coli cell line
• DNA Polymerases II have temporary function
when DNA Polymerases I and DNA Polymerases
III are not functional
• Still capable for doing synthesis on damage
template
• Participating in DNA repairing
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6. DNA Polymerases III
• DNA Polymerases III was identified later during
the experiment on mutant E.coli cell line.
• DNA Polymerases III is heterodimer enzyme
composed of ten different subunits
• It is true enzyme that is responsible for the
elongation process
• It also responsible for the polymerization of
Nucleotide and make most of the DNA during
replication.
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7. How DNA Polymerases I and III Work ? 7

8. Eukaryotic DNA Polymerases
• DNA polymerase a: Enzyme that makes short segment of
initiator DNA during replication of animal chromosomes
• DNA polymerase β: Implicated in repairing DNA, in base
excision repair and gap-filling synthesis.
DNA polymerase γ: Replicates and repairs mitochondrial
DNA and has proofreading 3'->5' exonuclease activity.
• DNA polymerase d: Enzyme that makes most of the DNA
when animal chromosomes are replicated
• DNA polymerase ε: Also highly possessive and has
proofreading 3'->5' exonuclease activity.
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9. Eukaryotic DNA polymerases 9

10. How Eukaryotic DNA Polymerases Work 10

11. RNA Polymerase
• Enzyme that synthesizes RNA using a DNA
template through a process called transcription
• RNA polymerase enzymes are essential to life and
are found in all organisms and many viruses
• It polymerizes ribonucleotide at the 3 end of an
RNA transcript
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12. Bacterial RNA Polymerases
• RNA polymerases is enzyme that synthesizes RNA
using a DNA template
• In bacteria only one RNA polymerases is
participate in transcription
• Bacterial RNA polymerases has four subunit.
• The sigma subunit of bacterial RNA polymerases
recognized promoter
• In bacteria it form monocistronic and polycistronic
mRNA
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13. Subunits Of RNA Polymerase's 13

14. How RNA Polymerases work in
Bacteria ? 14

15. Eukaryotic RNA Polymerases
There are three types of RNA polymerases used for
eukaryotic transcription
• RNA polymerase I Eukaryotic RNA polymerase that
transcribes the genes for the large ribosomal RNAs
• RNA polymerase II Eukaryotic RNA polymerase
that transcribes the genes encoding proteins
• RNA polymerase III Eukaryotic RNA polymerase
that transcribes the genes for 5S ribosomal RNA
and transfer RNA
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16. Prokaryotic vs Eukaryotic RNA
Polymerases 16

17. How RNA Polymerases work in
Eukaryotic ? 17

18. Any Question ? 18
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