Question

Which one of the following is correct about $H$-bonding in nucleotide?

• A. $A-T$, $G-C$
• B. $A-G$, $T-C$
• C. $G-T$, $A-C$
• D. $A-A$, $T-T$

Answer 1

Answer: (A)

$A-T$, $G-C$

The structure of DNA molecule is a double helix structure. In this structure double helix are made up of polynucleotide chains which are held together by $H$-bonds. In these helixes the adenine $\left(A\right)$ base is linked with thymine $\left(T\right)$ by two $H$-bonds and guanine $\left(G\right)$ is linked with cytocine $\left(C\right)$ by three $H$-bonds as $A\equiv T$, and $G\equiv C$.