Which one does not occur in lytic life cycle of a virulent DNA phage?

Options

A. The host cell lyses
B. New phages are released
C. Host cell produces a number of virions
D. Phage DNA integrates with host DNA

Answer

To solve the question "Which one does not occur in the lytic life cycle of a virulent DNA phage?", we need to analyze the options provided and understand the characteristics of the lytic life cycle of bacteriophages.

### Step-by-Step Solution:

1. **Understanding the Lytic Life Cycle**:
- The lytic life cycle is one of the two main life cycles of bacteriophages (virulent DNA phages). In this cycle, the phage infects a bacterial cell, replicates its DNA, and ultimately causes the host cell to lyse (burst), releasing new phage particles.

2. **Analyzing the Options**:
- **Option 1: Host cell lysis** - This occurs in the lytic cycle as the phage causes the bacterial cell to burst to release new phages.
- **Option 2: New phages are released** - This is also a characteristic of the lytic cycle, where multiple new phage particles are released after the host cell lysis.
- **Option 3: Host cell produces a number of virions** - In the lytic cycle, the host cell does produce virions (the complete virus particles), which are then released upon lysis.
- **Option 4: Phage DNA integrates with host DNA** - This process occurs during the lysogenic cycle, not the lytic cycle. In the lysogenic cycle, the phage DNA integrates into the host DNA and remains dormant.

3. **Identifying the Correct Answer**:
- Based on the analysis, the option that does not occur in the lytic life cycle is **Option 4: Phage DNA integrates with host DNA**.

### Final Answer:
The correct answer is **Option 4: Phage DNA integrates with host DNA**.

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