- Among the following which activity is absent in bacterial DNA polymerase I
(1) 5’-3’ Polymerase activity
(2) 3’-5’ Polymerase activity
(3) 5′-3’ Exonuclease activity
(4) 3′-5′ Exonuclease activity
Introduction
DNA Polymerase I (Pol I) in Escherichia coli is a multifunctional enzyme essential for DNA replication and repair. It possesses several enzymatic activities that enable it to synthesize DNA, proofread errors, and remove RNA primers. Understanding which activities are present or absent in Pol I is crucial for comprehending its role in bacterial DNA metabolism.
Enzymatic Activities of DNA Polymerase I
E. coli DNA Polymerase I has the following key activities:
-
5′→3′ Polymerase Activity
-
Adds nucleotides to the 3′ end of a growing DNA strand during DNA synthesis.
-
Essential for filling gaps after primer removal and DNA repair.
-
-
3′→5′ Exonuclease Activity (Proofreading)
-
Removes incorrectly incorporated nucleotides from the 3′ end, enhancing replication fidelity.
-
-
5′→3′ Exonuclease Activity
-
Removes RNA primers from Okazaki fragments and participates in nick translation during DNA repair.
-
Activity Absent in DNA Polymerase I
-
3′→5′ Polymerase Activity does not exist in DNA Polymerase I or any known DNA polymerase. DNA polymerases universally synthesize DNA in the 5′→3′ direction only.
-
Therefore, 3′→5′ polymerase activity is absent in bacterial DNA Polymerase I.
Summary Table of Activities
| Activity | Present in DNA Polymerase I? | Description |
|---|---|---|
| 5′→3′ Polymerase activity | Yes | DNA synthesis adding nucleotides 5′→3′ |
| 3′→5′ Polymerase activity | No | Does not exist; DNA synthesis only 5′→3′ |
| 5′→3′ Exonuclease activity | Yes | Removes RNA primers and DNA during repair |
| 3′→5′ Exonuclease activity | Yes | Proofreading to remove misincorporated bases |
Correct Answer
(2) 3′→5′ Polymerase activity
26 Comments
Manisha choudhary
July 28, 2025Done sir 👍🏻😀
anurag giri
July 29, 2025Ans 2 bcoz 3’-5’ ploymerase activity not exist in nature
Sneha Kumawat
July 29, 2025Polymerase 1 has activities ….5’to 3 polymerse activity …5′ to 3′ exoneuclease activity…3′ to 5 ‘ exoneuclease activity for proof reading,… 3 ‘ to 5 ‘ polymerase activity does not exist
Surbhi Rajawat
July 29, 2025Answer is 2nd because POL 1 doesn’t have 3′ to 5′ Polymerase activity
Khushi Agarwal
July 29, 20253′-5′ polymerase activity does not exist in pol 1
Mansukh Kapoor
July 29, 2025The correct answer is 2nd. there is no such activity which is present in the bacterial DNA pol.1
Heena
July 29, 20253-5 polymerase activity isn’t present in dna pol
Priti Khandal
July 29, 2025Option 2 is right
Priya Khandal
July 29, 20252 is correct
shruti sharma
July 30, 2025option 2
Payal Gaur
July 30, 20253′ to 5′ polymerase activity not present in DNA polymerase 1st
Deepika Sheoran
July 30, 2025Option 2 is correct
3’_5′ polymerase activity not +nt in Dna polymerase 1st.
3’_5′ polymerase activity is Absent in bacterial dna polymerase 1st.
Pratibha Sethiya
July 30, 2025Correct option is option (2)
3′-5′ polymerase activity
Aafreen
July 30, 2025DNA Polymerase I is known to 5′-3′ polymerase activity and 3′-5′ exonuclease activity for proof reading and 5′-3′ exonuclease activity for primer removal. So 2nd is correct answer
Diksha Chhipa
July 31, 20253 to 5 prime polymerisation activity is not present in dna pol1
Anisha jakhar
July 31, 20253′-5′ polymerase activity
Soniya Shekhawat
July 31, 2025In DNA polymerase 1 has not present 3’to5′ polymerase activity and remaining all are present
Santosh Saini
July 31, 2025Pol.1st does not exist 3′ to 5′ poly. Activity
Shivani
August 1, 2025Correct answer is 2 👍
Dipti Sharma
August 1, 20253′-5′ polymerase activity
Khushi Mehra
August 1, 2025In bacteria, DNA Polymerase does not have 3′-5′ Polymerase activity
Khushi Vaishnav
August 1, 2025DNA polymerases synthesize DNA in the 5′-3′ direction only.Therefore, 3′-5′ polymerase activity is absent in bacterial DNA Polymerase I.
Dharmpal Swami
August 1, 20253′ to 5′ polymerase activity absent in dna polymerase 1
Varsha tatla
August 3, 2025Option 2 bcz 3’5’polymerase activity not exist in biological system
Mahima Sharma
August 2, 20252
Deepika Sheoran
November 6, 20253′-5′ polymerase activity not present in DNA polymerase 1 st 3′-5′ polymerase activity is absent in bacterial DNA polymerase 1st.