In a DNA molecule , if the number of phosphodiester bonds is 198, it has …..... bases .

Options

A. 150
B. 100
C. 300
D. 400

Answer

To solve the problem of determining the number of bases in a DNA molecule given the number of phosphodiester bonds, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Relationship**: In a DNA molecule, phosphodiester bonds connect nucleotides. The number of phosphodiester bonds is related to the number of base pairs in the DNA. The formula that relates these two is:
\[ \text{Number of phosphodiester bonds} = 2n - 2 \]
where \( n \) is the number of base pairs.

2. **Identify Given Information**: The problem states that the number of phosphodiester bonds is 198. We can substitute this value into the formula:
\[ 198 = 2n - 2 \]

3. **Rearrange the Equation**: To isolate \( n \), we can rearrange the equation:
\[ 2n - 2 = 198 \]
Adding 2 to both sides gives:
\[ 2n = 200 \]

4. **Solve for \( n \)**: Now, divide both sides by 2 to find \( n \):
\[ n = \frac{200}{2} = 100 \]
This means there are 100 base pairs in the DNA molecule.

5. **Determine the Number of Bases**: Since each base pair consists of two bases (one from each strand of the DNA), the total number of bases is:
\[ \text{Total bases} = 2n = 2 \times 100 = 200 \]

### Conclusion:
The DNA molecule has **200 bases**.