What is not true w.r.t. the conditions associated with DNA entry into the host cell?

Options

A. DNA cannot pass through the cell membrane directly on its own
B. DNA is hydrophilic in nature
C. `Ca^(2)` ions helps in entry of DNA into the host cell
D. Heat shock completely blocks the entry of DNA into the host cell

Answer

To determine which statement is not true regarding the conditions associated with DNA entry into the host cell, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding DNA's Ability to Cross Cell Membranes**:
- **Statement**: "DNA cannot pass through the cell membrane directly on its own."
- **Analysis**: This statement is true. DNA is a large, hydrophilic molecule and cannot diffuse through the lipid bilayer of the cell membrane without assistance.

2. **Hydrophilicity of DNA**:
- **Statement**: "DNA is hydrophilic in nature."
- **Analysis**: This statement is also true. DNA contains a phosphate backbone that is negatively charged, making it hydrophilic (water-attracting) and unable to cross the membrane without help.

3. **Role of Calcium Ions**:
- **Statement**: "Calcium ions help in the entry of DNA into the host cell."
- **Analysis**: This statement is true. Calcium ions are often used in laboratory techniques to facilitate the uptake of DNA by creating transient pores in the cell membrane.

4. **Effect of Heat Shock**:
- **Statement**: "Heat shock completely blocks the entry of DNA into the host cell."
- **Analysis**: This statement is false. The heat shock method actually promotes the entry of DNA into the host cell by creating temporary pores in the membrane, allowing DNA to enter.

### Conclusion:
The statement that is not true regarding the conditions associated with DNA entry into the host cell is: **"Heat shock completely blocks the entry of DNA into the host cell."**

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