A single human cell has approximately ______ metre long thread of DNA distributed among its forty six chromosomes

Options

A. 2
B. 10
C. 1
D. 4.6

Answer

To solve the question regarding the approximate length of DNA in a single human cell distributed among its 46 chromosomes, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Number of Chromosomes**:
- A typical human cell is diploid, meaning it contains two sets of chromosomes. Humans have a total of 46 chromosomes in each diploid cell.

2. **Determine the Total Number of Base Pairs**:
- The human genome consists of approximately 6.4 billion base pairs.

3. **Calculate the Length of Each Base Pair**:
- Each base pair has an approximate length of about 0.34 nanometers.

4. **Calculate the Total Length of DNA**:
- To find the total length of DNA, multiply the total number of base pairs by the length of each base pair:
\[ \text{Total Length of DNA} = \text{Number of Base Pairs} \times \text{Length of Each Base Pair} \]
\[ \text{Total Length of DNA} = 6.4 \text{ billion} \times 0.34 \text{ nm} \]
\[ = 6.4 \times 10^9 \times 0.34 \times 10^{-9} \text{ meters} \]
\[ = 2.176 \text{ meters} \approx 2.2 \text{ meters} \]

5. **Conclusion**:
- The approximate length of DNA in a single human cell is about 2.2 meters, which is highly coiled and packed into the chromosomes.

### Final Answer:
A single human cell has approximately **2 meters** long thread of DNA distributed among its 46 chromosomes.