Medium INTEGER +4 / -1 PYQ · JEE Mains 2025

The total number of hydrogen bonds of a DNA-double Helix strand whose one strand has the following sequence of bases is ________.

$$5^{\prime}-\mathrm{G}-\mathrm{G}-\mathrm{C}-\mathrm{A}-\mathrm{A}-\mathrm{A}-\mathrm{T}-\mathrm{C}-\mathrm{G}-\mathrm{G}-\mathrm{C}-\mathrm{T}-\mathrm{A}-3^{\prime}$$

Answer (integer) 33

Solution

<p>Two nucleic acid chains are wound about each other and held together by H bonds between pair of bases.</p> <p>Adenine from two hydrogen bonds with thymine and Guanine form three hydrogen bond with cytosine.</p> <p>$$5^{\prime} \mathrm{G}-\mathrm{G}-\mathrm{C}-\mathrm{A}-\mathrm{A}-\mathrm{A}-\mathrm{T}-\mathrm{C}-\mathrm{G}-\mathrm{G}-\mathrm{C}-\mathrm{T}-\mathrm{A}-3^{\prime}$$</p> <p>In given DNA strand total seven guanine and cytosine bases which form total 21 H -bonds and six adenine and thymine base which will form total 12 H -bonds with other DNA strand.</p> <p>Total no. of H bonds $=7 \times 3+6 \times 2=33$</p> <p>Ans. 33</p>

About this question

Subject: Chemistry · Chapter: Biomolecules · Topic: Carbohydrates

This question is part of PrepWiser's free JEE Main question bank. 90 more solved questions on Biomolecules are available — start with the harder ones if your accuracy is >70%.

Drill 25 more like these. Every day. Free.

PrepWiser turns these solved questions into a daily practice loop. Chapter-wise drills, full mocks, AI doubt chat. No auto-renew.

Start free →