Okazaki fragments are synthesised on :-

Options

A. Leading stands of DNA only
B. Lagging staands of DNA only
C. Both leading and lagging starands of DNA
D. Complementary DNA

Answer

### Step-by-Step Solution:

1. **Understanding DNA Structure**: DNA is composed of two strands that run in opposite directions, known as antiparallel strands. One strand runs from the 5' to 3' direction, while the other runs from the 3' to 5' direction.

2. **DNA Replication Process**: During DNA replication, the double helix unwinds at the replication fork, creating two single strands. Each strand serves as a template for the synthesis of a new complementary strand.

3. **Role of DNA Polymerase**: DNA polymerase is the enzyme responsible for synthesizing new DNA strands. It can only add nucleotides in the 5' to 3' direction. This means that it synthesizes the new strand by adding nucleotides to the 3' end of the growing strand.

4. **Leading and Lagging Strands**:
- The strand that is synthesized continuously in the direction of the replication fork is called the **leading strand**.
- The other strand, which is synthesized in short segments (Okazaki fragments) in the opposite direction of the replication fork, is known as the **lagging strand**.

5. **Formation of Okazaki Fragments**: On the lagging strand, as the replication fork opens up, DNA polymerase synthesizes short segments of DNA called Okazaki fragments. These fragments are later joined together by the enzyme DNA ligase to form a continuous strand.

6. **Conclusion**: Therefore, Okazaki fragments are synthesized on the **lagging strand** during DNA replication.

### Final Answer:
Okazaki fragments are synthesized on the lagging strand.

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