Number of nucleosomes in a typical mammalian cell

Options

A. `3.3 xx 10^7`
B. `1.65 xx 10^9`
C. `3.3 xx 10^9`
D. `1.65 xx 10^9`

Answer

To determine the number of nucleosomes in a typical mammalian cell, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of Nucleosomes**:
- Nucleosomes are the basic units of DNA packaging in eukaryotic cells. Each nucleosome consists of a segment of DNA wrapped around a core of histone proteins.

2. **Identify the Amount of DNA in a Cell**:
- A typical mammalian cell contains approximately \(6.6 \times 10^9\) base pairs of DNA.

3. **Determine the Number of Base Pairs per Nucleosome**:
- Each nucleosome contains about 200 base pairs of DNA.

4. **Calculate the Number of Nucleosomes**:
- To find the total number of nucleosomes, divide the total number of base pairs by the number of base pairs per nucleosome:
\[ \text{Number of Nucleosomes} = \frac{\text{Total Base Pairs}}{\text{Base Pairs per Nucleosome}} = \frac{6.6 \times 10^9}{200} \]

5. **Perform the Calculation**:
- Performing the division:
\[ \text{Number of Nucleosomes} = \frac{6.6 \times 10^9}{200} = 3.3 \times 10^7 \]

6. **Conclusion**:
- Therefore, the number of nucleosomes in a typical mammalian cell is \(3.3 \times 10^7\).

### Final Answer:
The number of nucleosomes in a typical mammalian cell is \(3.3 \times 10^7\).

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