Q39 / 160 · AP EAMCET 2013 · Chemistry

The number of hydrogen bonds between guanine and cytosine; and between adenine and thymine in DNA is

  • A
    $1.2$
  • Correct answer
    B
    $3,2$
  • C
    $3,1$
  • D
    $2,1$

Solution

The only possible pairing in DNA are between $\mathrm{G}$ (guanine) and $\mathrm{C}$ (cytosine) through three $\mathrm{H}$-bonds i.e., $(\mathrm{C} \equiv \mathrm{G})$ and between A (adenine) and $\mathrm{T}$ (thymine) through two $\mathrm{H}$-bonds (i.e., $\mathrm{A}=\mathrm{T}$ ) as shown in figure. Figure

Hence, the correct answer is option: 'B'.

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