Assertion : Use of chitinase enzyme is necessary for isolation of DNA from yeast cells but not in case of Spirogyra.
Reason : Fungal cell wall is made up of fungal cellulose or chitin.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Assertion:**
- The assertion states that the use of chitinase enzyme is necessary for the isolation of DNA from yeast cells but not from Spirogyra.
- Yeast is a type of fungus, and its cell wall is composed of chitin.

2. **Role of Chitinase:**
- Chitinase is an enzyme that breaks down chitin, which is a structural component of the cell wall in fungi.
- To isolate DNA from yeast cells, the cell wall must be digested to release the DNA, hence chitinase is required.

3. **Analyzing Spirogyra:**
- Spirogyra is an alga, not a fungus.
- The cell wall of Spirogyra is not made of chitin; instead, it is primarily composed of cellulose.

4. **Conclusion on the Assertion:**
- Since chitin is present in yeast (fungal cells) but absent in Spirogyra (algal cells), the assertion is correct: chitinase is needed for yeast but not for Spirogyra.

5. **Understanding the Reason:**
- The reason states that the fungal cell wall is made up of fungal cellulose or chitin.
- This statement is partially correct; while it correctly identifies chitin as a component of the fungal cell wall, it inaccurately includes "fungal cellulose" which is not a standard term. The main component is chitin.

6. **Evaluating the Relationship:**
- The reason provided supports the assertion because it explains why chitinase is necessary for yeast but not for Spirogyra.
- Therefore, both the assertion and reason are true, and the reason correctly explains the assertion.

7. **Final Answer:**
- The correct answer is option A: Both assertion and reason are true, and the reason is the correct explanation for the assertion.