The Okazaki fragments in DNA chain growth

Options

A. polymerize in the 3'-to'5 direction and forms replication fork.
B. prove semi-conservative nature of DNA replication
C. polymerize in the 5'-to-3' direction and explain 3'-to-5' DNA replication
D. result in transcription

Answer

**Step-by-Step Solution:**

1. **Understanding Okazaki Fragments**:
- Okazaki fragments are short sequences of DNA nucleotides that are synthesized discontinuously on the lagging strand during DNA replication.

2. **Direction of Polymerization**:
- DNA polymerase synthesizes DNA in the 5' to 3' direction. This means that nucleotides are added to the 3' end of the growing DNA strand.

3. **Lagging Strand Synthesis**:
- The lagging strand is synthesized in short segments (Okazaki fragments) because DNA replication can only occur in the 5' to 3' direction. As the replication fork opens up, the lagging strand is synthesized in the opposite direction to the fork movement.

4. **Joining of Okazaki Fragments**:
- After the Okazaki fragments are synthesized, they are later joined together by the enzyme DNA ligase, which seals the gaps between the fragments to create a continuous DNA strand.

5. **Analyzing the Options**:
- **Option A**: "Polymerize in the 3' to 5' direction and forms replication fork" - This is incorrect because DNA is synthesized in the 5' to 3' direction.
- **Option B**: "Proves semi-conservative nature of DNA replication" - This is incorrect as this relates to the overall mechanism of DNA replication, not specifically to Okazaki fragments.
- **Option C**: "Polymerize in the 5' to 3' direction and explain 3' to 5' DNA replication" - This is correct because it accurately describes how Okazaki fragments are formed on the lagging strand.
- **Option D**: "Resulting transcription" - This is incorrect as transcription refers to the synthesis of RNA from DNA, which is a different process.

6. **Conclusion**:
- The correct answer is **Option C**, which states that Okazaki fragments polymerize in the 5' to 3' direction on the lagging strand.

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