Arrange the steps of isolation of DNA from the source cell :
( I) Precipitation of DNA with chilled ethanol.
(II) Treatment of DNA strands with protease and RNAase.
(III) Treatment of DNA strands with restriction endonuclease.
(IV) Isolation of DNA from bacterial cells by the treatment of lysozyme.

Options

A. (IV), (I), (II), (III)
B. (II), (I), (IV), (III)
C. (IV), (I), (III), (II)
D. (IV), (II), (I), (III)

Answer

To arrange the steps of isolation of DNA from the source cell, we need to follow a logical sequence of actions that lead to the successful extraction and purification of DNA. Here’s the step-by-step solution:

### Step-by-Step Solution:

1. **Isolation of DNA from bacterial cells by the treatment of lysozyme (IV)**:
- The first step involves breaking down the bacterial cell wall using lysozyme. This allows the release of cellular contents, including DNA, into the solution.

2. **Treatment of DNA strands with protease and RNAase (II)**:
- After the cells are lysed, the next step is to treat the mixture with protease and RNAase. Protease will digest proteins, and RNAase will degrade RNA, leaving behind only the DNA.

3. **Precipitation of DNA with chilled ethanol (I)**:
- Once the DNA is isolated from proteins and RNA, chilled ethanol is added to the solution. This causes the DNA to precipitate out of the solution, forming visible strands.

4. **Treatment of DNA strands with restriction endonuclease (III)**:
- Finally, after the DNA has been precipitated and purified, it can be treated with restriction endonucleases. These enzymes cut the DNA into smaller fragments for further analysis or manipulation.

### Final Order:
The correct order of steps for the isolation of DNA is:
**IV → II → I → III**