If the length of a double helical DNA if 1.7 meters then the number of base pairs present in the DNA is

Options

A. `5xx10^(9)`
B. `1.7 xx 10^(9)`
C. `3.4 xx 10^(9)`
D. `1.7 xx 10^(5)`

Answer

To find the number of base pairs in a double helical DNA of length 1.7 meters, we can follow these steps:

### Step 1: Convert the length of DNA from meters to angstroms.
1 meter is equal to \(10^{10}\) angstroms. Therefore, we convert 1.7 meters to angstroms:
\[ 1.7 \, \text{meters} = 1.7 \times 10^{10} \, \text{angstroms} \]

### Step 2: Know the length of one base pair.
The length of one base pair in DNA is approximately \(3.4\) angstroms.

### Step 3: Calculate the number of base pairs.
To find the number of base pairs, we can use the formula:
\[ \text{Number of base pairs} = \frac{\text{Total length of DNA in angstroms}}{\text{Length of one base pair in angstroms}} \]

Substituting the values we have:
\[ \text{Number of base pairs} = \frac{1.7 \times 10^{10} \, \text{angstroms}}{3.4 \, \text{angstroms}} \]

### Step 4: Perform the division.
Calculating the above expression:
\[ \text{Number of base pairs} = \frac{1.7 \times 10^{10}}{3.4} = 0.5 \times 10^{10} \]

### Step 5: Simplify the result.
We can express \(0.5 \times 10^{10}\) in scientific notation:
\[ 0.5 \times 10^{10} = 5 \times 10^{9} \]

### Final Answer:
The number of base pairs present in the DNA is \(5 \times 10^{9}\).

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