If percentage of cytosine is 18 %, then percentage of thymine will be

Options

A. `32 %`
B. `64 %`
C. `36 %`
D. `23 %`

Answer

To solve the problem of finding the percentage of thymine when the percentage of cytosine is given as 18%, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Given Information:**
- Percentage of Cytosine (C) = 18%

2. **Apply Chargaff's Rules:**
- According to Chargaff's rules, in DNA:
- The percentage of Cytosine (C) is equal to the percentage of Guanine (G).
- The percentage of Adenine (A) is equal to the percentage of Thymine (T).

3. **Calculate the Percentage of Guanine:**
- Since C = G, the percentage of Guanine (G) is also 18%.

4. **Calculate the Total Percentage of Cytosine and Guanine:**
- Total percentage of C and G = C + G = 18% + 18% = 36%

5. **Calculate the Remaining Percentage for Adenine and Thymine:**
- The total percentage of all four bases (A, T, C, G) in DNA must equal 100%.
- Therefore, the percentage of Adenine and Thymine combined = 100% - (C + G) = 100% - 36% = 64%.

6. **Set Up the Equation for Adenine and Thymine:**
- Since A = T, we can represent the total percentage of A and T as:
- A + T = 64%
- Substituting T for A gives us:
- T + T = 64%
- 2T = 64%

7. **Solve for Thymine:**
- Divide both sides by 2:
- T = 64% / 2 = 32%

8. **Conclusion:**
- The percentage of Thymine (T) is 32%.

### Final Answer:
The percentage of Thymine is **32%**.

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