7. During DNA replication, events at the replication fork require different types of enzymes having specialized functions except
(1) DNA polymerase III
(2) DNA gyrase
(3) DNA ligase
(4) DNA glycosylase
Introduction
DNA replication is a highly coordinated process involving multiple enzymes working together at the replication fork to ensure accurate and efficient duplication of the genome. While enzymes like DNA polymerase III, DNA gyrase, and DNA ligase play crucial roles at the replication fork, some enzymes are involved in other DNA-related processes. This article explains the functions of these enzymes and identifies the one that is not directly involved in the replication fork activities.
Enzymes Involved in DNA Replication Fork Activities
1. DNA Polymerase III
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The primary enzyme responsible for synthesizing new DNA strands by adding nucleotides complementary to the template strand.
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Works on both the leading and lagging strands.
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Has proofreading activity to ensure replication fidelity.
2. DNA Gyrase
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A type of topoisomerase II that relieves the supercoiling tension generated ahead of the replication fork due to unwinding.
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Prevents DNA tangling and allows smooth progression of the replication machinery.
3. DNA Ligase
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Joins Okazaki fragments on the lagging strand by forming phosphodiester bonds.
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Seals nicks in the sugar-phosphate backbone to create a continuous DNA strand.
Enzyme Not Directly Involved: DNA Glycosylase
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DNA glycosylase is involved in base excision repair (BER), a DNA repair pathway.
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It recognizes and removes damaged or inappropriate bases by cleaving the glycosidic bond, initiating repair.
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Not involved in DNA synthesis or replication fork progression.
Summary Table
| Enzyme | Role in DNA Replication Fork | Involved at Replication Fork? |
|---|---|---|
| DNA Polymerase III | DNA synthesis on leading and lagging strands | Yes |
| DNA Gyrase | Relieves supercoiling ahead of replication fork | Yes |
| DNA Ligase | Joins Okazaki fragments | Yes |
| DNA Glycosylase | DNA base excision repair | No |
Conclusion
During DNA replication, enzymes such as DNA polymerase III, DNA gyrase, and DNA ligase are essential for synthesis, unwinding, and joining DNA strands at the replication fork. However, DNA glycosylase, which functions in DNA repair, is not directly involved in the replication fork activities.
Answer:
The enzyme not involved in replication fork activities is (4) DNA glycosylase.
37 Comments
Manisha choudhary
July 25, 2025😄😄
Diksha chhip
July 29, 2025DNA GLYCOSYLASE enzyme is used in DNA repair system while dna pol3 gyrase and ligase are used in replication mech
Anjani sharma
July 30, 2025Answer 4 is correct as it is used in repair not in replication
Diksha chhipa
July 29, 2025DNA GLYCOSYLASE enzyme is used in DNA repair system while dna pol3 gyrase and ligase are used in replication mech
Diksha chhipa
July 29, 2025DNA GLYCOSYLASE enzyme is used in DNA repair system while dna pol3 gyrase and ligase are used in replication mech.
Mansukh Kapoor
July 29, 2025The correct answer is DNA glycosylase because this does not use in replication fork rather it is used in DNA repair
Pratibha Sethiya
July 29, 2025Correct option is option (4)
DNA glycosylase involved in DNA repair, specifically in the base excision repair (BER) pathway, where they recognize and remove damaged or incorrect bases from DNA. While crucial for maintaining genome integrity, they are not directly involved in the process of DNA synthesis at the replication fork itself.
Khushi Agarwal
July 29, 2025Option 4 dna glycosylase enzyme is not used in dna replication
Divyanshi Vaishnav
July 29, 2025Dna glycosylase is correct answer because this enzyme’s work is dna repairing so this is not directly involved in dna replication fork activities
Heena
July 29, 2025Dna glycosylase is not involved in dna replication process
Aafreen g
July 30, 2025DNA polymerase 3rd, DNA Gyrase and DNA ligase are used for synthesizing of strand, unwind and join ozaki fragments at the replication fork.
DNA glycosylase is used in base repair not involved in DNA synthesis.
Vijay Marmat
August 2, 20254 done ✔️
Surbhi Rajawat
July 29, 2025All the enzymes are used in replication except for DNA glycolase which is option 4
HIMANI FAUJDAR
July 29, 2025DNA glycosylase is the answer because all three involved in DNA replication but glycosylase present in DNA repairing
Priti Khandal
July 29, 2025Yes option 4 is right bcz DNA glycosyrase use in DNA base excision repair
Priya Khandal
July 29, 2025D is right dna glycosylase i read explanation
shruti sharma
July 29, 2025DNA glycolase is not involved in DNA replication because it involved in base excision repair
Khushi Mehra
July 29, 2025Dna polymerase 3, Dna gyrase , dna ligase are involved in dna replication but dna glycosylase does not.
Khushi Vaishnav
July 29, 2025DNA gylocolase enzyme, because it is not directly involved in replication fork activities
Priyanka choudhary
July 29, 2025The right answer is DNA glycosylase because of this yeh DNA repair m damage bases ko remove krne m helpfull hota h
Monika jangid
July 29, 2025Dna glycosylase enz. Not involved in replication fork activities bcoz the function of this enzyme is dna repair it cannot directly involved in the replication fork activities
Priya Dhakad
July 30, 2025The answer is DNA glycosylase is used in DNA repairing and all 3 enzymes are used in DNA replication
Sneha Kumawat
July 30, 2025Correct answer is DNA glycosalase it is use in DNA repair specially BER pathway
Payal Gaur
July 30, 2025DNA Glycosylase is used in DNA base excision repair pathway not in DNA replication
Niti tanwar
July 30, 2025Right answer is 4 bzc dna glycosylase is used dna repair
anurag giri
July 30, 2025Ans 4 bcoz glycosylase use in dna repair mechanism
Deepika Sheoran
July 30, 2025Dna glycosylase is an enzyme that helps fixed damaged dna by removing the wrong or damaged parts .
When there’s a mistake in the dna like a broken base this enzyme finds it and takes it out afterward, the dna can be repaired and go back to being correct.
..
Dharmpal Swami
July 30, 2025Dna glycosylase works in base excision repair mechanism and not required during replication
Rakesh Dhaka
July 30, 2025DNA glycosylase use in dna repair mechanism
Aman Choudhary
July 30, 2025Option 4 DNA Glycosylase it is used in repair mechanism
Anisha jakhar
July 31, 2025Option 4
Dipti Sharma
July 31, 2025Enzymes such as DNA polymerase III, DNA gyrase, and DNA ligase are essential at the replication fork. However, DNA glycosylase, is not directly involved in the replication fork, it involves in DNA repair mechanism.
Mahima Sharma
August 2, 2025Glycosylage
Soniya Shekhawat
August 3, 2025DNA glycosylase is involved in DNA repairing So 4 is correct .
Anita Choudhary
August 28, 2025Answer 4 is correct because glycosylase is involved in repair not required in replication .
Alec
August 30, 2025Dna glycosylase functions in dna repair is not directly involved in the replication fork.
Deepika Sheoran
November 6, 2025DNA glycosylase is an enzyme that helps fixed damaged DNA by removing the wrong or damaged parts.
When ther’s mistake in the DNA like a broken base this enzyme finds it and takes it out afterword, the DNA can be required and go back to being correct.