Chapter 12, Problem 28Q

Interpretation Introduction

Interpretation: Using Figure 13.7, why adenine-thymine base pairs are less stable than cytosine-guanine base pairs should be explained.

Concept Introduction:

The four major nitrogen-containing bases are:

Adenine:

It is represented with the letter “A”

Guanine:

It is represented with the letter “G”.

Thymine:

It is represented with the letter “T”.

Cytosine:

It is represented with the letter “C”.

Complementary bases:

• • Adenine is the complementary base of Thymine.
• • Cytosine is the complementary base of Guanine.
• • In DNA, Adenine always makes a double bond with thymine ($A=T$) and cytosine always makes triple bond with guanine $\left(G\equiv C\right)$

Hydrogen bonding between complementary bases:

The bases of nucleotides of one DNA strand makes hydrogen bonding with their respective complementary bases of the nucleotides of the other DNA strand. This hydrogen bonding keeps the two DNA strands of a DNA helix rigid and stable.