Based on this information following statements are made:
- (i) represents the leading strand while (ii), (ii) and (iv) represent the Okazaki fragments.
- Among the Okazaki fragments, synthesis of (iv) occurs prior to the synthesis of (iii) and (i)
- Among the Okazaki fragments, synthesis of (ii) occurs prior to the synthesis of (iii) and (iv).
Which one of the following options represents the correct statement(s)?
(1) A only (2) B only
(3) A and B(4) A and C
The Replication Fork: Leading and Lagging Strands
At the DNA replication fork, two new strands are synthesized:
-
Leading strand: Synthesized continuously in the same direction as the replication fork movement.
-
Lagging strand: Synthesized discontinuously in short segments called Okazaki fragments, in the direction opposite to fork movement2567.
Analyzing the Statements
Statement A
-
(i) represents the leading strand while (ii), (iii), and (iv) represent the Okazaki fragments.
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This is correct. The leading strand is synthesized continuously, while the lagging strand is made in fragments (Okazaki fragments)2567.
Statement B
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Among the Okazaki fragments, synthesis of (iv) occurs prior to the synthesis of (iii) and (ii).
-
This is incorrect. On the lagging strand, the Okazaki fragment closest to the origin (fork junction) is synthesized first. As the fork opens up, new Okazaki fragments are initiated further away from the fork. Thus, the fragment farthest from the fork (typically labeled as (ii)) is synthesized first, and the one closest to the fork (typically (iv)) is synthesized last.
Statement C
-
Among the Okazaki fragments, synthesis of (ii) occurs prior to the synthesis of (iii) and (iv).
-
This is correct. The Okazaki fragment farthest from the replication fork (usually labeled (ii)) is synthesized first, followed by (iii), then (iv), as the fork progresses2567.
Correct Option
Based on the analysis:
-
A and C are correct.
Final Answer
(4) A and C
Summary Table
| Statement | Correct? | Explanation |
|---|---|---|
| A | Yes | Leading strand is continuous; Okazaki fragments are discontinuous. |
| B | No | The Okazaki fragment closest to the fork is synthesized last, not first. |
| C | Yes | The fragment farthest from the fork is synthesized first. |
Keywords: replication fork, Okazaki fragments, leading strand, lagging strand, DNA replication, synthesis order, DNA polymerase, discontinuous synthesis
22 Comments
Manisha choudhary
July 28, 2025Done sir concept clear sir 🤓👍🏻
Mansukh Kapoor
July 29, 2025The correct answer is option 4th
Priti Khandal
July 29, 2025Yes sir Option 4 is right
Priya Khandal
July 29, 2025Done sir 4 is right
Pratibha
July 30, 2025Correct option is option (3)
Statement 1.
The leading strand is synthesized continuously, while the lagging strand is made in fragments (Okazaki fragments).
Statement 2.
the fragment farthest from the fork is synthesized first, and the one closest to the fork is synthesized last.
So the( iv) is synthesized first than (ii)
anurag giri
July 30, 2025Ans 4 bcoz Leading strand is continuous; Okazaki fragments are discontinuous and The fragment farthest from the fork is synthesized first
Khushi Agarwal
July 30, 2025A and c are correct
Vanshika Sharma
July 30, 2025Option 3 is correct
Divya rani
July 30, 20254th is right anwer because 1st is leading strand which is continuous and the fragment closest to the fork is formed firstly
Priya Dhakad
July 31, 2025Option is 4 because 1 st is leading strand which is continuous and 2and 4th are represent lagging strand which is discontinuous so (A) is right and (C) is also correct becoz fragment farthest from the fork is synthesized first.
Deepika Sheoran
July 30, 2025Option 3 is correct answer.
shruti sharma
July 30, 2025ONLY A
Aafreen
July 30, 2025Ans- 4th
Ankita Pareek
July 31, 2025A and C is correct because it says 1st is leading strand which it correct and in option c it says 2nd formed prior toh third and fourth also correct because the fragment which is far from the fork form first
Santosh Saini
July 31, 2025A and C is the correct statement because leading strand is synthesized in the direction of replication fork and continuous while lagging strand id discontinuous and okazaki fragments farthest from rep. fork
Khushi Vaishnav
July 31, 2025Option A is correct because Leading strand is continuous.
And option C is correct because fragment farthest from the fork is synthesized first
Kajal
July 31, 2025Option A and C is right
A is leading and rest are indicating lagging strand and ii will synthesis first then the iii and iv
Dipti Sharma
August 1, 2025Correct option is 3
A and B statements are correct and c is incorrect because in lagging strand iv will synthesize first.
Dp
August 1, 2025Statement A&B are write
Dp
August 1, 2025Statement A&B are write
Mitali Saini
August 2, 2025Correct option is A and C
Deepika Sheoran
November 6, 2025Option 3 rd is correct