Number of base pairs present in total DNA of human cell (human genome) is around

Options

A. 4.3
B. 3.6
C. 2.1
D. 5.8

Answer

To determine the number of base pairs present in the total DNA of a human cell (human genome), we can follow these steps:

### Step 1: Understand the Length of DNA in Human Cells
The total length of DNA in a haploid human cell is approximately 3 billion base pairs. For a diploid cell, which contains two sets of chromosomes, this number doubles. However, for our calculation, we will focus on the haploid number first.

### Step 2: Calculate the Length of DNA
The length of DNA in a haploid cell can be calculated using the formula:
\[ \text{Length of DNA} = \text{Number of base pairs} \times \text{Base pair constant} \]
The base pair constant (the distance between two base pairs) is approximately 0.34 nanometers (or \(3.4 \times 10^{-9}\) meters).

### Step 3: Convert Length to Nanometers
To find the total length of DNA in nanometers:
\[ \text{Length in nanometers} = 3 \times 10^9 \text{ base pairs} \times 0.34 \text{ nm/base pair} \]
Calculating this gives:
\[ \text{Length in nanometers} = 1.02 \times 10^9 \text{ nm} \]

### Step 4: Calculate the Total Length for Diploid Cells
For diploid cells, the total length of DNA is doubled:
\[ \text{Total Length for Diploid} = 2 \times 1.02 \times 10^9 \text{ nm} = 2.04 \times 10^9 \text{ nm} \]

### Step 5: Calculate the Number of Base Pairs
To find the number of base pairs in a diploid cell, we can use the formula:
\[ \text{Number of base pairs} = \frac{\text{Total Length of DNA}}{\text{Base pair constant}} \]
Substituting the values:
\[ \text{Number of base pairs} = \frac{2.04 \times 10^9 \text{ nm}}{0.34 \text{ nm/base pair}} \]

### Step 6: Perform the Calculation
Calculating the above expression gives:
\[ \text{Number of base pairs} \approx 6 \times 10^9 \text{ base pairs} \]
However, since we are looking for the number of base pairs in a haploid cell, we revert back to the original estimate of approximately 3 billion base pairs.

### Conclusion
The total number of base pairs present in the human genome is approximately 3.6 billion.

### Final Answer
The number of base pairs present in total DNA of a human cell (human genome) is around **3.6 billion**.

---