JEE Main 2023 · Chemistry · Biomolecules and Polymers · easy

A segment of double-stranded DNA is 10 base pairs long and contains 4 adenine bases. Assuming standard Watson-Crick pairing, the total number of…

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A segment of double-stranded DNA is

10

base pairs long and contains

4

adenine bases. Assuming standard Watson-Crick pairing, the total number of hydrogen bonds holding the two strands together in this segment is

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Answer: (A) $26$

In a double strand, adenine pairs with thymine, so

A=T

. The segment has

10

base pairs;

4

adenines in the whole duplex means

4

A-T pairs? Here the

4

adenines are

4

A–T pairs (each A-T pair has exactly one adenine), leaving

6

G-C pairs. A-T pairs are joined by

2

H-bonds and G-C pairs by

3

. Total

=4\times2+6\times3=8+18=26

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