For the strand separation and stabilisation during DNA replication which of the following set of enzymes and proteins are required?

Options

A. SSBP, gyrase , primase
B. Toposiomerase,helicase, ligase
C. Gyrase , ligase, primase
D. Topoisomerase, helicase, SSBP

Answer

To answer the question regarding the enzymes and proteins required for strand separation and stabilization during DNA replication, we can break down the process step by step.

### Step-by-Step Solution:

1. **Understanding DNA Structure**: DNA is a double-stranded molecule that needs to be unwound for replication. This unwinding creates single strands that must be stabilized to prevent them from re-annealing or forming secondary structures.

2. **Role of Helicase**: The first enzyme involved in strand separation is **helicase**. Helicase unwinds the double helix by breaking the hydrogen bonds between the nucleotide bases, separating the two strands of DNA.

3. **Function of Single-Strand Binding Proteins (SSBPs)**: Once the DNA strands are separated by helicase, **single-strand binding proteins (SSBPs)** bind to the exposed single strands. Their primary function is to stabilize these strands and prevent them from re-forming a double helix or folding back on themselves.

4. **Topoisomerase and Gyrase**: As the DNA unwinds, it creates tension ahead of the replication fork. **Topoisomerase** (and specifically **gyrase** in bacteria) alleviates this tension by making cuts in the DNA, allowing it to unwind and then resealing it. This prevents supercoiling and ensures smooth progression of the replication fork.

5. **Exclusion of Other Enzymes**: Other enzymes mentioned, such as **primase** and **ligase**, play roles in different aspects of DNA replication. Primase synthesizes RNA primers necessary for DNA polymerase to start replication, and ligase joins Okazaki fragments on the lagging strand but does not participate in strand separation or stabilization.

6. **Conclusion**: The enzymes and proteins specifically required for strand separation and stabilization during DNA replication are helicase, single-strand binding proteins, and topoisomerase (or gyrase).

### Final Answer:
The correct set of enzymes and proteins required for strand separation and stabilization during DNA replication includes:
- Helicase
- Single-Strand Binding Proteins (SSBPs)
- Topoisomerase (or Gyrase)

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