Question

The number of hydrogen bonds present in the sequence of a stretch of a double helical DNA 5${}^1$ ATGCCTAA 3${}^1$, is:

• A. 16
• B. 19
• C. 24
• D. 20

Answer 1

Answer: (B)

19

The number of hydrogen bonds present in the sequence of a stretch of a double helical DNA 5${}^1$ ATGCCTAA 3${}^1$ is 19. A always combines with T by two hydrogen bonds and G combines with C by three hydrogen bonds. Thus, we can simply sum them up to get the required result.