A fragment of double-stranded DNA molecule contains 12 phosphates and 2 adenines. Given this information, what is the total number of purine bases, deoxyribose sugars and hydrogen bonds respectively, present in the described DNA molecule?
A) 12, 24, 28
B) 4, 12, 12
C) 6, 12, 20
D) 6, 16, 12
E) 6, 12, 16
IMAT 2023 · Question 26
Q26 - Structure of DNA and RNA
Pinned
The correct answer is E) 6, 12, 16.
Each nucleotide has one phosphate, so 12 phosphates means 12 nucleotides: 12 deoxyriboses and 6 base pairs.
With 2 adenines, there are 2 thymines, so 2 A–T pairs. The other 8 bases make 4 G–C pairs.
Purines (A + G): 2 + 4 = 6
Hydrogen bonds: 2 A–T × 2 + 4 G–C × 3 = 4 + 12 = 16
6, 12, 16
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