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 the number of nucleosomes present in the DNA of a human cell, we can follow these steps:

### Step 1: Understand the Structure of Nucleosomes
Nucleosomes are the basic structural units of eukaryotic chromosomes. Each nucleosome consists of a segment of DNA wrapped around a core of histone proteins.

### Step 2: Know the Amount of DNA in a Human Cell
A human cell contains approximately \(6.6 \times 10^9\) base pairs of DNA.

### Step 3: Determine the Number of Base Pairs per Nucleosome
It is known that about 200 base pairs of DNA are wrapped around histone proteins to form one nucleosome.

### Step 4: Calculate the Number of Nucleosomes
To find the total number of nucleosomes, we can use the formula:

\[ \text{Number of Nucleosomes} = \frac{\text{Total Base Pairs}}{\text{Base Pairs per Nucleosome}} \]

Substituting the known values:

\[ \text{Number of Nucleosomes} = \frac{6.6 \times 10^9 \text{ base pairs}}{200 \text{ base pairs/nucleosome}} \]

### Step 5: Perform the Calculation
Calculating the above expression:

\[ \text{Number of Nucleosomes} = \frac{6.6 \times 10^9}{200} = 3.3 \times 10^7 \]

### Conclusion
Thus, the number of nucleosomes present in the DNA of a human cell is approximately \(3.3 \times 10^7\).

### Final Answer
**The number of nucleosomes in a human cell is approximately \(3.3 \times 10^7\).**

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