Theoretically, how many nucleosomes do you imagine are present in a mammalian cell?

Options

A. equal to number of chromosomes
B. equal to number of nucleotides
C. equal to number of histone molecules
D. equal to number of base pairs divided by 200

Answer

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

### Step 1: Understand the Structure of a Nucleosome
A nucleosome consists of a segment of DNA wrapped around a core of histone proteins. Each nucleosome typically contains about 200 base pairs of DNA.

### Step 2: Determine the Total Number of Base Pairs in a Mammalian Genome
For example, the human genome contains approximately 3 billion base pairs (3 x 10^9 base pairs).

### Step 3: Calculate the Number of Nucleosomes
Since each nucleosome is associated with about 200 base pairs of DNA, we can calculate the estimated number of nucleosomes by dividing the total number of base pairs by the number of base pairs per nucleosome.

\[ \text{Number of Nucleosomes} = \frac{\text{Total Base Pairs}}{\text{Base Pairs per Nucleosome}} = \frac{3 \times 10^9 \text{ base pairs}}{200 \text{ base pairs/nucleosome}} \]

### Step 4: Perform the Calculation
\[ \text{Number of Nucleosomes} = \frac{3 \times 10^9}{200} = 15 \times 10^6 = 15,000,000 \]

### Step 5: Conclusion
The estimated number of nucleosomes present in a mammalian cell, such as a human cell, is around 15 million.