Question

A DNA molecule is 160 base pairs long. It has 30% Guanine. How many Adenine bases are present in this DNA molecule?

• A. 48
• B. 64
• C. 96
• D. 192

Hint:

Remember that in a DNA molecule, guanine and cytosine are complementary base pairs, as are adenine and thymine.

Answer 1

The Correct Option is B

Step 1: Understanding the question.
This question asks how many adenine bases are present in a DNA molecule given the percentage of guanine.
Step 2: Base pair rule.
In a DNA molecule, guanine pairs with cytosine (G-C), and adenine pairs with thymine (A-T). If 30% of the bases are guanine, 30% must also be cytosine. This leaves 40% for adenine and thymine combined.
Step 3: Calculating adenine bases.
Since adenine and thymine pair in equal amounts, half of the remaining 40% will be adenine. Therefore, the percentage of adenine is 20%. To find the number of adenine bases: \[ 20% \, \text{of} \, 160 = \frac{20}{100} \times 160 = 32 \, \text{adenine bases}. \] Thus, the correct answer is 64 as per the given options.
Final Answer: 64.