How many nucleosomes are present in DNA of a human cell?

Options

A. `6.6 xx 10^9`
B. `3.3 xx 10^9`
C. `6.6 xx 10^7`
D. `3.3 xx 10^7`

Answer

To determine how many nucleosomes are present in the DNA of a human cell, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Nucleosomes**:
- A nucleosome consists of a segment of DNA wrapped around a core of histone proteins. This structure helps in packaging the DNA into a compact form.

2. **Human DNA Length**:
- The total length of DNA in a human cell is approximately 2 meters when fully extended.

3. **Nucleosome Structure**:
- Each nucleosome is made up of about 147 base pairs of DNA wrapped around a histone octamer.

4. **Estimating the Number of Nucleosomes**:
- It is estimated that about 30 million nucleosomes are present in the DNA of a human cell. This is based on the fact that approximately 3/4 of the human DNA is occupied by nucleosomes.

5. **Conclusion**:
- Therefore, the number of nucleosomes in a human cell is approximately 30 million.

### Final Answer:
The number of nucleosomes present in the DNA of a human cell is approximately **30 million**.